Add m-esr52 at 52.6.0

23 files changed, 2397 insertions, 0 deletions

diff --git a/dom/grid/Grid.cpp b/dom/grid/Grid.cpp
new file mode 100644
index 000000000..d10d8b581
--- /dev/null
+++ b/dom/grid/Grid.cpp
@@ -0,0 +1,122 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Grid.h"
+
+#include "GridArea.h"
+#include "GridDimension.h"
+#include "mozilla/dom/GridBinding.h"
+#include "nsGridContainerFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(Grid, mParent, mRows, mCols, mAreas)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(Grid)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(Grid)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(Grid)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+Grid::Grid(nsISupports* aParent,
+           nsGridContainerFrame* aFrame)
+  : mParent(do_QueryInterface(aParent))
+  , mRows(new GridDimension(this))
+  , mCols(new GridDimension(this))
+{
+  MOZ_ASSERT(aFrame,
+    "Should never be instantiated with a null nsGridContainerFrame");
+
+  // Construct areas first, because lines may need to reference them
+  // to extract additional names for boundary lines.
+
+  // Add implicit areas first. Track the names that we add here, because
+  // we will ignore future explicit areas with the same name.
+  nsTHashtable<nsStringHashKey> namesSeen;
+  nsGridContainerFrame::ImplicitNamedAreas* implicitAreas =
+    aFrame->GetImplicitNamedAreas();
+  if (implicitAreas) {
+    for (auto iter = implicitAreas->Iter(); !iter.Done(); iter.Next()) {
+      auto& areaInfo = iter.Data();
+      namesSeen.PutEntry(areaInfo.mName);
+      GridArea* area = new GridArea(this,
+                                    areaInfo.mName,
+                                    GridDeclaration::Implicit,
+                                    areaInfo.mRowStart,
+                                    areaInfo.mRowEnd,
+                                    areaInfo.mColumnStart,
+                                    areaInfo.mColumnEnd);
+      mAreas.AppendElement(area);
+    }
+  }
+
+  // Add explicit areas next, as long as they don't have the same name
+  // as the implicit areas, because the implicit values override what was
+  // initially available in the explicit areas.
+  nsGridContainerFrame::ExplicitNamedAreas* explicitAreas =
+    aFrame->GetExplicitNamedAreas();
+  if (explicitAreas) {
+    for (auto& areaInfo : *explicitAreas) {
+      if (!namesSeen.Contains(areaInfo.mName)) {
+        GridArea* area = new GridArea(this,
+                                      areaInfo.mName,
+                                      GridDeclaration::Explicit,
+                                      areaInfo.mRowStart,
+                                      areaInfo.mRowEnd,
+                                      areaInfo.mColumnStart,
+                                      areaInfo.mColumnEnd);
+        mAreas.AppendElement(area);
+      }
+    }
+  }
+
+  // Now construct the tracks and lines.
+  const ComputedGridTrackInfo* rowTrackInfo =
+    aFrame->GetComputedTemplateRows();
+  const ComputedGridLineInfo* rowLineInfo =
+    aFrame->GetComputedTemplateRowLines();
+  mRows->SetTrackInfo(rowTrackInfo);
+  mRows->SetLineInfo(rowTrackInfo, rowLineInfo, mAreas, true);
+
+  const ComputedGridTrackInfo* columnTrackInfo =
+    aFrame->GetComputedTemplateColumns();
+  const ComputedGridLineInfo* columnLineInfo =
+    aFrame->GetComputedTemplateColumnLines();
+  mCols->SetTrackInfo(columnTrackInfo);
+  mCols->SetLineInfo(columnTrackInfo, columnLineInfo, mAreas, false);
+}
+
+Grid::~Grid()
+{
+}
+
+JSObject*
+Grid::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridBinding::Wrap(aCx, this, aGivenProto);
+}
+
+GridDimension*
+Grid::Rows() const
+{
+  return mRows;
+}
+
+GridDimension*
+Grid::Cols() const
+{
+  return mCols;
+}
+
+void
+Grid::GetAreas(nsTArray<RefPtr<GridArea>>& aAreas) const
+{
+  aAreas = mAreas;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/Grid.h b/dom/grid/Grid.h
new file mode 100644
index 000000000..426f33ec2
--- /dev/null
+++ b/dom/grid/Grid.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Grid_h
+#define mozilla_dom_Grid_h
+
+#include "GridArea.h"
+#include "mozilla/dom/Element.h"
+#include "nsGridContainerFrame.h"
+#include "nsISupports.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class GridDimension;
+
+class Grid : public nsISupports
+           , public nsWrapperCache
+{
+public:
+  explicit Grid(nsISupports* aParent, nsGridContainerFrame* aFrame);
+
+protected:
+  virtual ~Grid();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Grid)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  Element* GetParentObject()
+  {
+    return mParent;
+  }
+
+  GridDimension* Rows() const;
+  GridDimension* Cols() const;
+  void GetAreas(nsTArray<RefPtr<GridArea>>& aAreas) const;
+
+protected:
+  nsCOMPtr<Element> mParent;
+  RefPtr<GridDimension> mRows;
+  RefPtr<GridDimension> mCols;
+  nsTArray<RefPtr<GridArea>> mAreas;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_Grid_h */
diff --git a/dom/grid/GridArea.cpp b/dom/grid/GridArea.cpp
new file mode 100644
index 000000000..d8a7eca76
--- /dev/null
+++ b/dom/grid/GridArea.cpp
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridArea.h"
+#include "mozilla/dom/GridBinding.h"
+#include "Grid.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridArea, mParent)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridArea)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridArea)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridArea)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridArea::GridArea(Grid* aParent,
+                   const nsString& aName,
+                   GridDeclaration aType,
+                   uint32_t aRowStart,
+                   uint32_t aRowEnd,
+                   uint32_t aColumnStart,
+                   uint32_t aColumnEnd)
+  : mParent(aParent)
+  , mName(aName)
+  , mType(aType)
+  , mRowStart(aRowStart)
+  , mRowEnd(aRowEnd)
+  , mColumnStart(aColumnStart)
+  , mColumnEnd(aColumnEnd)
+{
+}
+
+GridArea::~GridArea()
+{
+}
+
+JSObject*
+GridArea::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridAreaBinding::Wrap(aCx, this, aGivenProto);
+}
+
+void
+GridArea::GetName(nsString& aName) const
+{
+  aName = mName;
+}
+
+GridDeclaration
+GridArea::Type() const
+{
+  return mType;
+}
+
+uint32_t
+GridArea::RowStart() const
+{
+  return mRowStart;
+}
+
+uint32_t
+GridArea::RowEnd() const
+{
+  return mRowEnd;
+}
+
+uint32_t
+GridArea::ColumnStart() const
+{
+  return mColumnStart;
+}
+
+uint32_t
+GridArea::ColumnEnd() const
+{
+  return mColumnEnd;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridArea.h b/dom/grid/GridArea.h
new file mode 100644
index 000000000..19b610ca2
--- /dev/null
+++ b/dom/grid/GridArea.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridArea_h
+#define mozilla_dom_GridArea_h
+
+#include "mozilla/dom/GridBinding.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class Grid;
+
+class GridArea : public nsISupports
+               , public nsWrapperCache
+{
+public:
+  explicit GridArea(Grid *aParent,
+                    const nsString& aName,
+                    GridDeclaration aType,
+                    uint32_t aRowStart,
+                    uint32_t aRowEnd,
+                    uint32_t aColumnStart,
+                    uint32_t aColumnEnd);
+
+protected:
+  virtual ~GridArea();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridArea)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  Grid* GetParentObject()
+  {
+    return mParent;
+  }
+
+  void GetName(nsString& aName) const;
+  GridDeclaration Type() const;
+  uint32_t RowStart() const;
+  uint32_t RowEnd() const;
+  uint32_t ColumnStart() const;
+  uint32_t ColumnEnd() const;
+
+protected:
+  RefPtr<Grid> mParent;
+  const nsString mName;
+  const GridDeclaration mType;
+  const uint32_t mRowStart;
+  const uint32_t mRowEnd;
+  const uint32_t mColumnStart;
+  const uint32_t mColumnEnd;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridTrack_h */
diff --git a/dom/grid/GridDimension.cpp b/dom/grid/GridDimension.cpp
new file mode 100644
index 000000000..040f3a380
--- /dev/null
+++ b/dom/grid/GridDimension.cpp
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridDimension.h"
+
+#include "Grid.h"
+#include "GridLines.h"
+#include "GridTracks.h"
+#include "mozilla/dom/GridBinding.h"
+#include "nsGridContainerFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridDimension, mParent, mLines, mTracks)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridDimension)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridDimension)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridDimension)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridDimension::GridDimension(Grid* aParent)
+  : mParent(aParent)
+  , mLines(new GridLines(this))
+  , mTracks(new GridTracks(this))
+{
+  MOZ_ASSERT(aParent, "Should never be instantiated with a null Grid");
+}
+
+GridDimension::~GridDimension()
+{
+}
+
+JSObject*
+GridDimension::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridDimensionBinding::Wrap(aCx, this, aGivenProto);
+}
+
+GridLines*
+GridDimension::Lines() const
+{
+  return mLines;
+}
+
+GridTracks*
+GridDimension::Tracks() const
+{
+  return mTracks;
+}
+
+void
+GridDimension::SetTrackInfo(const ComputedGridTrackInfo* aTrackInfo)
+{
+  mTracks->SetTrackInfo(aTrackInfo);
+}
+
+void
+GridDimension::SetLineInfo(const ComputedGridTrackInfo* aTrackInfo,
+                           const ComputedGridLineInfo* aLineInfo,
+                           const nsTArray<RefPtr<GridArea>>& aAreas,
+                           bool aIsRow)
+{
+  mLines->SetLineInfo(aTrackInfo, aLineInfo, aAreas, aIsRow);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridDimension.h b/dom/grid/GridDimension.h
new file mode 100644
index 000000000..7a3373521
--- /dev/null
+++ b/dom/grid/GridDimension.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridDimension_h
+#define mozilla_dom_GridDimension_h
+
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+
+struct ComputedGridTrackInfo;
+
+namespace dom {
+
+class Grid;
+class GridLines;
+class GridTracks;
+
+class GridDimension : public nsISupports
+                    , public nsWrapperCache
+{
+public:
+  explicit GridDimension(Grid* aParent);
+
+protected:
+  virtual ~GridDimension();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridDimension)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  Grid* GetParentObject()
+  {
+    return mParent;
+  }
+
+  GridLines* Lines() const;
+  GridTracks* Tracks() const;
+
+  void SetTrackInfo(const ComputedGridTrackInfo* aTrackInfo);
+  void SetLineInfo(const ComputedGridTrackInfo* aTrackInfo,
+                   const ComputedGridLineInfo* aLineInfo,
+                   const nsTArray<RefPtr<GridArea>>& aAreas,
+                   bool aIsRow);
+
+protected:
+  RefPtr<Grid> mParent;
+  RefPtr<GridLines> mLines;
+  RefPtr<GridTracks> mTracks;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridDimension_h */
diff --git a/dom/grid/GridLine.cpp b/dom/grid/GridLine.cpp
new file mode 100644
index 000000000..8e1e5ed7c
--- /dev/null
+++ b/dom/grid/GridLine.cpp
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridLine.h"
+
+#include "GridLines.h"
+#include "mozilla/dom/GridBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridLine, mParent)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridLine)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridLine)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridLine)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridLine::GridLine(GridLines *aParent)
+  : mParent(aParent)
+  , mStart(0.0)
+  , mBreadth(0.0)
+  , mType(GridDeclaration::Implicit)
+  , mNumber(0)
+{
+  MOZ_ASSERT(aParent, "Should never be instantiated with a null GridLines");
+}
+
+GridLine::~GridLine()
+{
+}
+
+void
+GridLine::GetNames(nsTArray<nsString>& aNames) const
+{
+  aNames = mNames;
+}
+
+JSObject*
+GridLine::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridLineBinding::Wrap(aCx, this, aGivenProto);
+}
+
+double
+GridLine::Start() const
+{
+  return mStart;
+}
+
+double
+GridLine::Breadth() const
+{
+  return mBreadth;
+}
+
+GridDeclaration
+GridLine::Type() const
+{
+  return mType;
+}
+
+uint32_t
+GridLine::Number() const
+{
+  return mNumber;
+}
+
+void
+GridLine::SetLineValues(const nsTArray<nsString>& aNames,
+                        double aStart,
+                        double aBreadth,
+                        uint32_t aNumber,
+                        GridDeclaration aType)
+{
+  mNames = aNames;
+  mStart = aStart;
+  mBreadth = aBreadth;
+  mNumber = aNumber;
+  mType = aType;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridLine.h b/dom/grid/GridLine.h
new file mode 100644
index 000000000..858f9d5e0
--- /dev/null
+++ b/dom/grid/GridLine.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridLine_h
+#define mozilla_dom_GridLine_h
+
+#include "mozilla/dom/GridBinding.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class GridLines;
+
+class GridLine : public nsISupports
+               , public nsWrapperCache
+{
+public:
+  explicit GridLine(GridLines* aParent);
+
+protected:
+  virtual ~GridLine();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridLine)
+
+  void GetNames(nsTArray<nsString>& aNames) const;
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  GridLines* GetParentObject()
+  {
+    return mParent;
+  }
+
+  double Start() const;
+  double Breadth() const;
+  GridDeclaration Type() const;
+  uint32_t Number() const;
+
+  void SetLineValues(const nsTArray<nsString>& aNames,
+                     double aStart,
+                     double aBreadth,
+                     uint32_t aNumber,
+                     GridDeclaration aType);
+
+protected:
+  RefPtr<GridLines> mParent;
+  nsTArray<nsString> mNames;
+  double mStart;
+  double mBreadth;
+  GridDeclaration mType;
+  uint32_t mNumber;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridLine_h */
diff --git a/dom/grid/GridLines.cpp b/dom/grid/GridLines.cpp
new file mode 100644
index 000000000..fac645c64
--- /dev/null
+++ b/dom/grid/GridLines.cpp
@@ -0,0 +1,250 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridLines.h"
+
+#include "GridDimension.h"
+#include "GridLine.h"
+#include "mozilla/dom/GridBinding.h"
+#include "nsGridContainerFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridLines, mParent, mLines)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridLines)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridLines)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridLines)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridLines::GridLines(GridDimension* aParent)
+  : mParent(aParent)
+{
+  MOZ_ASSERT(aParent,
+    "Should never be instantiated with a null GridDimension");
+}
+
+GridLines::~GridLines()
+{
+}
+
+JSObject*
+GridLines::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridLinesBinding::Wrap(aCx, this, aGivenProto);
+}
+
+uint32_t
+GridLines::Length() const
+{
+  return mLines.Length();
+}
+
+GridLine*
+GridLines::Item(uint32_t aIndex)
+{
+  return mLines.SafeElementAt(aIndex);
+}
+
+GridLine*
+GridLines::IndexedGetter(uint32_t aIndex,
+                         bool& aFound)
+{
+  aFound = aIndex < mLines.Length();
+  if (!aFound) {
+    return nullptr;
+  }
+  return mLines[aIndex];
+}
+
+void
+GridLines::SetLineInfo(const ComputedGridTrackInfo* aTrackInfo,
+                       const ComputedGridLineInfo* aLineInfo,
+                       const nsTArray<RefPtr<GridArea>>& aAreas,
+                       bool aIsRow)
+{
+  MOZ_ASSERT(aLineInfo);
+  mLines.Clear();
+
+  if (!aTrackInfo) {
+    return;
+  }
+
+  uint32_t trackCount = aTrackInfo->mEndFragmentTrack -
+                        aTrackInfo->mStartFragmentTrack;
+
+  // If there is at least one track, line count is one more
+  // than the number of tracks.
+  if (trackCount > 0) {
+    nscoord lastTrackEdge = 0;
+    nscoord startOfNextTrack;
+    uint32_t repeatIndex = 0;
+    uint32_t numRepeatTracks = aTrackInfo->mRemovedRepeatTracks.Length();
+    uint32_t numAddedLines = 0;
+
+    for (uint32_t i = aTrackInfo->mStartFragmentTrack;
+         i < aTrackInfo->mEndFragmentTrack + 1;
+         i++) {
+      uint32_t line1Index = i + 1;
+
+      startOfNextTrack = (i < aTrackInfo->mEndFragmentTrack) ?
+                         aTrackInfo->mPositions[i] :
+                         lastTrackEdge;
+
+      nsTArray<nsString> lineNames;
+      lineNames = aLineInfo->mNames.SafeElementAt(i, nsTArray<nsString>());
+
+      // Add in names from grid areas where this line is used as a boundary.
+      for (auto area : aAreas) {
+        bool haveNameToAdd = false;
+        nsAutoString nameToAdd;
+        area->GetName(nameToAdd);
+        if (aIsRow) {
+          if (area->RowStart() == line1Index) {
+            haveNameToAdd = true;
+            nameToAdd.AppendLiteral("-start");
+          } else if (area->RowEnd() == line1Index) {
+            haveNameToAdd = true;
+            nameToAdd.AppendLiteral("-end");
+          }
+        } else {
+          if (area->ColumnStart() == line1Index) {
+            haveNameToAdd = true;
+            nameToAdd.AppendLiteral("-start");
+          } else if (area->ColumnEnd() == line1Index) {
+            haveNameToAdd = true;
+            nameToAdd.AppendLiteral("-end");
+          }
+        }
+
+        if (haveNameToAdd && !lineNames.Contains(nameToAdd)) {
+          lineNames.AppendElement(nameToAdd);
+        }
+      }
+
+      if (i >= aTrackInfo->mRepeatFirstTrack &&
+          repeatIndex < numRepeatTracks) {
+        numAddedLines += AppendRemovedAutoFits(aTrackInfo,
+                                               aLineInfo,
+                                               lastTrackEdge,
+                                               repeatIndex,
+                                               numRepeatTracks,
+                                               lineNames);
+      }
+
+      RefPtr<GridLine> line = new GridLine(this);
+      mLines.AppendElement(line);
+      line->SetLineValues(
+        lineNames,
+        nsPresContext::AppUnitsToDoubleCSSPixels(lastTrackEdge),
+        nsPresContext::AppUnitsToDoubleCSSPixels(startOfNextTrack -
+                                                 lastTrackEdge),
+        line1Index + numAddedLines,
+        (
+          // Implicit if there are no explicit tracks, or if the index
+          // is before the first explicit track, or after
+          // a track beyond the last explicit track.
+          (aTrackInfo->mNumExplicitTracks == 0) ||
+          (i < aTrackInfo->mNumLeadingImplicitTracks) ||
+          (i > aTrackInfo->mNumLeadingImplicitTracks +
+               aTrackInfo->mNumExplicitTracks) ?
+            GridDeclaration::Implicit :
+            GridDeclaration::Explicit
+        )
+      );
+
+      if (i < aTrackInfo->mEndFragmentTrack) {
+        lastTrackEdge = aTrackInfo->mPositions[i] + aTrackInfo->mSizes[i];
+      }
+    }
+  }
+}
+
+uint32_t
+GridLines::AppendRemovedAutoFits(const ComputedGridTrackInfo* aTrackInfo,
+                                 const ComputedGridLineInfo* aLineInfo,
+                                 nscoord aLastTrackEdge,
+                                 uint32_t& aRepeatIndex,
+                                 uint32_t aNumRepeatTracks,
+                                 nsTArray<nsString>& aLineNames)
+{
+  // Check to see if lineNames contains ALL of the before line names.
+  bool alreadyHasBeforeLineNames = true;
+  for (const auto& beforeName : aLineInfo->mNamesBefore) {
+    if (!aLineNames.Contains(beforeName)) {
+      alreadyHasBeforeLineNames = false;
+      break;
+    }
+  }
+
+  bool extractedExplicitLineNames = false;
+  nsTArray<nsString> explicitLineNames;
+  uint32_t linesAdded = 0;
+  while (aRepeatIndex < aNumRepeatTracks &&
+         aTrackInfo->mRemovedRepeatTracks[aRepeatIndex]) {
+    // If this is not the very first call to this function, and if we
+    // haven't already added a line this call, pull all the explicit
+    // names to pass along to the next line that will be added after
+    // this function completes.
+    if (aRepeatIndex > 0 &&
+        linesAdded == 0) {
+      // Find the names that didn't match the before or after names,
+      // and extract them.
+      for (const auto& name : aLineNames) {
+        if (!aLineInfo->mNamesBefore.Contains(name) &&
+            !aLineInfo->mNamesAfter.Contains(name)) {
+          explicitLineNames.AppendElement(name);
+        }
+      }
+      for (const auto& extractedName : explicitLineNames) {
+        aLineNames.RemoveElement(extractedName);
+      }
+      extractedExplicitLineNames = true;
+    }
+
+    // If this is the second or later time through, or didn't already
+    // have before names, add them.
+    if (linesAdded > 0 || !alreadyHasBeforeLineNames) {
+      aLineNames.AppendElements(aLineInfo->mNamesBefore);
+    }
+
+    RefPtr<GridLine> line = new GridLine(this);
+    mLines.AppendElement(line);
+    line->SetLineValues(
+      aLineNames,
+      nsPresContext::AppUnitsToDoubleCSSPixels(aLastTrackEdge),
+      nsPresContext::AppUnitsToDoubleCSSPixels(0),
+      aTrackInfo->mRepeatFirstTrack + aRepeatIndex + 1,
+      GridDeclaration::Explicit
+    );
+
+    // No matter what, the next line should have the after names associated
+    // with it. If we go through the loop again, the before names will also
+    // be added.
+    aLineNames = aLineInfo->mNamesAfter;
+    aRepeatIndex++;
+
+    linesAdded++;
+  }
+  aRepeatIndex++;
+
+  if (extractedExplicitLineNames) {
+    // Pass on the explicit names we saved to the next explicit line.
+    aLineNames.AppendElements(explicitLineNames);
+  }
+
+  if (alreadyHasBeforeLineNames && linesAdded > 0) {
+    // If we started with before names, pass them on to the next explicit
+    // line.
+    aLineNames.AppendElements(aLineInfo->mNamesBefore);
+  }
+  return linesAdded;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridLines.h b/dom/grid/GridLines.h
new file mode 100644
index 000000000..921168204
--- /dev/null
+++ b/dom/grid/GridLines.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridLines_h
+#define mozilla_dom_GridLines_h
+
+#include "nsTArray.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class GridDimension;
+class GridLine;
+
+class GridLines : public nsISupports
+                , public nsWrapperCache
+{
+public:
+  explicit GridLines(GridDimension* aParent);
+
+protected:
+  virtual ~GridLines();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridLines)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  GridDimension* GetParentObject()
+  {
+    return mParent;
+  }
+
+  uint32_t Length() const;
+  GridLine* Item(uint32_t aIndex);
+  GridLine* IndexedGetter(uint32_t aIndex, bool& aFound);
+
+  void SetLineInfo(const ComputedGridTrackInfo* aTrackInfo,
+                   const ComputedGridLineInfo* aLineInfo,
+                   const nsTArray<RefPtr<GridArea>>& aAreas,
+                   bool aIsRow);
+
+protected:
+  uint32_t AppendRemovedAutoFits(const ComputedGridTrackInfo* aTrackInfo,
+                                 const ComputedGridLineInfo* aLineInfo,
+                                 nscoord aLastTrackEdge,
+                                 uint32_t& aRepeatIndex,
+                                 uint32_t aNumRepeatTracks,
+                                 nsTArray<nsString>& aLineNames);
+
+  RefPtr<GridDimension> mParent;
+  nsTArray<RefPtr<GridLine>> mLines;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridLines_h */
diff --git a/dom/grid/GridTrack.cpp b/dom/grid/GridTrack.cpp
new file mode 100644
index 000000000..328af7d5c
--- /dev/null
+++ b/dom/grid/GridTrack.cpp
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridTrack.h"
+
+#include "GridTracks.h"
+#include "mozilla/dom/GridBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridTrack, mParent)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridTrack)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridTrack)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridTrack)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridTrack::GridTrack(GridTracks* aParent)
+  : mParent(aParent)
+  , mStart(0.0)
+  , mBreadth(0.0)
+  , mType(GridDeclaration::Implicit)
+  , mState(GridTrackState::Static)
+{
+  MOZ_ASSERT(aParent, "Should never be instantiated with a null GridTracks");
+}
+
+GridTrack::~GridTrack()
+{
+}
+
+JSObject*
+GridTrack::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridTrackBinding::Wrap(aCx, this, aGivenProto);
+}
+
+double
+GridTrack::Start() const
+{
+  return mStart;
+}
+
+double
+GridTrack::Breadth() const
+{
+  return mBreadth;
+}
+
+GridDeclaration
+GridTrack::Type() const
+{
+  return mType;
+}
+
+GridTrackState
+GridTrack::State() const
+{
+  return mState;
+}
+
+void
+GridTrack::SetTrackValues(double aStart,
+                          double aBreadth,
+                          GridDeclaration aType,
+                          GridTrackState aState)
+{
+  mStart = aStart;
+  mBreadth = aBreadth;
+  mType = aType;
+  mState = aState;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridTrack.h b/dom/grid/GridTrack.h
new file mode 100644
index 000000000..d1825c5ad
--- /dev/null
+++ b/dom/grid/GridTrack.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridTrack_h
+#define mozilla_dom_GridTrack_h
+
+#include "mozilla/dom/GridBinding.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class GridTracks;
+
+class GridTrack : public nsISupports
+                , public nsWrapperCache
+{
+public:
+  explicit GridTrack(GridTracks *parent);
+
+protected:
+  virtual ~GridTrack();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridTrack)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  GridTracks* GetParentObject()
+  {
+    return mParent;
+  }
+
+  double Start() const;
+  double Breadth() const;
+  GridDeclaration Type() const;
+  GridTrackState State() const;
+
+  void SetTrackValues(double aStart,
+                      double aBreadth,
+                      GridDeclaration aType,
+                      GridTrackState aState);
+
+protected:
+  RefPtr<GridTracks> mParent;
+  double mStart;
+  double mBreadth;
+  GridDeclaration mType;
+  GridTrackState mState;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridTrack_h */
diff --git a/dom/grid/GridTracks.cpp b/dom/grid/GridTracks.cpp
new file mode 100644
index 000000000..8b607973c
--- /dev/null
+++ b/dom/grid/GridTracks.cpp
@@ -0,0 +1,134 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GridTracks.h"
+
+#include "GridDimension.h"
+#include "GridTrack.h"
+#include "mozilla/dom/GridBinding.h"
+#include "nsGridContainerFrame.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(GridTracks, mParent, mTracks)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(GridTracks)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(GridTracks)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(GridTracks)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+GridTracks::GridTracks(GridDimension *aParent)
+  : mParent(aParent)
+{
+  MOZ_ASSERT(aParent,
+    "Should never be instantiated with a null GridDimension");
+}
+
+GridTracks::~GridTracks()
+{
+}
+
+JSObject*
+GridTracks::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return GridTracksBinding::Wrap(aCx, this, aGivenProto);
+}
+
+uint32_t
+GridTracks::Length() const
+{
+  return mTracks.Length();
+}
+
+GridTrack*
+GridTracks::Item(uint32_t aIndex)
+{
+  return mTracks.SafeElementAt(aIndex);
+}
+
+GridTrack*
+GridTracks::IndexedGetter(uint32_t aIndex,
+                          bool& aFound)
+{
+  aFound = aIndex < mTracks.Length();
+  if (!aFound) {
+    return nullptr;
+  }
+  return mTracks[aIndex];
+}
+
+void
+GridTracks::SetTrackInfo(const ComputedGridTrackInfo* aTrackInfo)
+{
+  // rebuild the tracks based on aTrackInfo
+  mTracks.Clear();
+
+  if (!aTrackInfo) {
+    return;
+  }
+
+  nscoord lastTrackEdge = 0;
+  uint32_t repeatIndex = 0;
+  auto AppendRemovedAutoFits = [this, &aTrackInfo, &lastTrackEdge,
+                                &repeatIndex]()
+  {
+    uint32_t numRepeatTracks = aTrackInfo->mRemovedRepeatTracks.Length();
+    // Add in removed auto-fit tracks
+    while (repeatIndex < numRepeatTracks &&
+         aTrackInfo->mRemovedRepeatTracks[repeatIndex]) {
+
+      RefPtr<GridTrack> track = new GridTrack(this);
+      mTracks.AppendElement(track);
+      track->SetTrackValues(
+        nsPresContext::AppUnitsToDoubleCSSPixels(lastTrackEdge),
+        nsPresContext::AppUnitsToDoubleCSSPixels(0),
+        GridDeclaration::Explicit,
+        GridTrackState::Removed
+      );
+      repeatIndex++;
+    }
+    repeatIndex++;
+  };
+
+  for (size_t i = aTrackInfo->mStartFragmentTrack;
+       i < aTrackInfo->mEndFragmentTrack;
+       i++) {
+    if (i >= aTrackInfo->mRepeatFirstTrack) {
+      // Append removed auto-fit tracks, if appropriate. The
+      // AppendRemovedAutoFits function exits early once it has been called
+      // aTrackInfo->mRemovedRepeatTracks.Length() times -- a check we don't
+      // replicate here or at subsequent calling sites.
+      AppendRemovedAutoFits();
+    }
+
+    RefPtr<GridTrack> track = new GridTrack(this);
+    mTracks.AppendElement(track);
+    track->SetTrackValues(
+      nsPresContext::AppUnitsToDoubleCSSPixels(aTrackInfo->mPositions[i]),
+      nsPresContext::AppUnitsToDoubleCSSPixels(aTrackInfo->mSizes[i]),
+      (
+        // Implicit if index is before the first explicit track, or after
+        // the last explicit track.
+        (i < aTrackInfo->mNumLeadingImplicitTracks) ||
+        (i >= aTrackInfo->mNumLeadingImplicitTracks +
+              aTrackInfo->mNumExplicitTracks) ?
+          GridDeclaration::Implicit :
+          GridDeclaration::Explicit
+      ),
+      GridTrackState(aTrackInfo->mStates[i])
+    );
+
+    lastTrackEdge = aTrackInfo->mPositions[i] + aTrackInfo->mSizes[i];
+  }
+
+  // Append any trailing removed auto-fit tracks.
+  AppendRemovedAutoFits();
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/grid/GridTracks.h b/dom/grid/GridTracks.h
new file mode 100644
index 000000000..ab7faeacd
--- /dev/null
+++ b/dom/grid/GridTracks.h
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_GridTracks_h
+#define mozilla_dom_GridTracks_h
+
+#include "nsTArray.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+
+struct ComputedGridTrackInfo;
+
+namespace dom {
+
+class GridDimension;
+class GridTrack;
+
+class GridTracks : public nsISupports
+                 , public nsWrapperCache
+{
+public:
+  explicit GridTracks(GridDimension* aParent);
+
+protected:
+  virtual ~GridTracks();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(GridTracks)
+
+  virtual JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
+  GridDimension* GetParentObject()
+  {
+    return mParent;
+  }
+
+  uint32_t Length() const;
+  GridTrack* Item(uint32_t aIndex);
+  GridTrack* IndexedGetter(uint32_t aIndex, bool& aFound);
+
+  void SetTrackInfo(const mozilla::ComputedGridTrackInfo* aTrackInfo);
+
+protected:
+  RefPtr<GridDimension> mParent;
+  nsTArray<RefPtr<GridTrack>> mTracks;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_GridTracks_h */
diff --git a/dom/grid/moz.build b/dom/grid/moz.build
new file mode 100644
index 000000000..96d5c3151
--- /dev/null
+++ b/dom/grid/moz.build
@@ -0,0 +1,33 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+MOCHITEST_CHROME_MANIFESTS += ['test/chrome.ini']
+
+EXPORTS.mozilla.dom += [
+    'Grid.h',
+    'GridArea.h',
+    'GridDimension.h',
+    'GridLine.h',
+    'GridLines.h',
+    'GridTrack.h',
+    'GridTracks.h',
+]
+
+UNIFIED_SOURCES += [
+    'Grid.cpp',
+    'GridArea.cpp',
+    'GridDimension.cpp',
+    'GridLine.cpp',
+    'GridLines.cpp',
+    'GridTrack.cpp',
+    'GridTracks.cpp',
+]
+
+LOCAL_INCLUDES += [
+    '/layout/generic',
+]
+
+FINAL_LIBRARY = 'xul'
diff --git a/dom/grid/test/chrome.ini b/dom/grid/test/chrome.ini
new file mode 100644
index 000000000..2241cf9eb
--- /dev/null
+++ b/dom/grid/test/chrome.ini
@@ -0,0 +1,7 @@
+[chrome/test_grid_areas.html]
+[chrome/test_grid_fragmentation.html]
+[chrome/test_grid_implicit.html]
+[chrome/test_grid_lines.html]
+[chrome/test_grid_object.html]
+[chrome/test_grid_repeats.html]
+[chrome/test_grid_tracks.html]
diff --git a/dom/grid/test/chrome/test_grid_areas.html b/dom/grid/test/chrome/test_grid_areas.html
new file mode 100644
index 000000000..2f5d8ea44
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_areas.html
@@ -0,0 +1,143 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	width: 600px;
+	height: 600px;
+	grid-gap: 20px;
+	grid-template-columns: 50px 1fr 50px;
+	grid-template-rows: 1fr 1fr 1fr;
+	grid-template-areas: "areaA areaA ....."
+						 "areaB areaC areaC"
+						 "areaB areaC areaC";
+	background-color: #f00;
+}
+.box {
+	background-color: #444;
+	color: #fff;
+}
+.a {
+	grid-area: areaA;
+}
+.b {
+	grid-area: areaB;
+}
+.c {
+	grid-area: areaC;
+}
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	var wrapper = document.getElementById("wrapper");
+	var grid = wrapper.getGridFragments()[0];
+
+	// test existence of property
+	isnot(typeof(grid.areas), "undefined", "Grid.areas property exists.");
+
+	if (typeof(grid.areas) != "undefined") {
+		// test that the right number of areas are reported
+		is(grid.areas.length, 3, "3 areas are reported.");
+
+		if (grid.areas.length == 3) {
+			// test area names
+			is(grid.areas[0].name, "areaA", "Area 0 has proper name.");
+			is(grid.areas[1].name, "areaB", "Area 1 has proper name.");
+			is(grid.areas[2].name, "areaC", "Area 2 has proper name.");
+
+			// test area types
+			is(grid.areas[0].type, "explicit", "Area 0 is explicit.");
+			is(grid.areas[1].type, "explicit", "Area 1 is explicit.");
+			is(grid.areas[2].type, "explicit", "Area 2 is explicit.");
+
+			// test numbers of start and end lines
+			is(grid.areas[0].rowStart, 1, "Area 0 has start row line of 1.");
+			is(grid.areas[0].rowEnd, 2, "Area 0 has end row line of 2.");
+			is(grid.areas[0].columnStart, 1, "Area 0 has start column line of 1.");
+			is(grid.areas[0].columnEnd, 3, "Area 0 has end column line of 3.");
+
+			is(grid.areas[1].rowStart, 2, "Area 1 has start row line of 2.");
+			is(grid.areas[1].rowEnd, 4, "Area 1 has end row line of 4.");
+			is(grid.areas[1].columnStart, 1, "Area 1 has start column line of 1.");
+			is(grid.areas[1].columnEnd, 2, "Area 1 has end column line of 2.");
+
+			is(grid.areas[2].rowStart, 2, "Area 2 has start row line of 2.");
+			is(grid.areas[2].rowEnd, 4, "Area 2 has end row line of 4.");
+			is(grid.areas[2].columnStart, 2, "Area 2 has start column line of 2.");
+			is(grid.areas[2].columnEnd, 4, "Area 2 has end column line of 4.");
+			
+			// test names of all the row lines
+			isnot(grid.rows.lines[0].names.indexOf("areaA-start"), -1,
+				"Grid row line 1 has the name 'areaA-start'."
+			);
+			
+			isnot(grid.rows.lines[1].names.indexOf("areaA-end"), -1,
+				"Grid row line 2 has the name 'areaA-end'."
+			);
+			isnot(grid.rows.lines[1].names.indexOf("areaB-start"), -1,
+				"Grid row line 2 has the name 'areaB-start'."
+			);
+			isnot(grid.rows.lines[1].names.indexOf("areaC-start"), -1,
+				"Grid row line 2 has the name 'areaC-start'."
+			);
+			
+			is(grid.rows.lines[2].names.length, 0, "Grid row line 3 has no names.");
+			
+			isnot(grid.rows.lines[3].names.indexOf("areaB-end"), -1,
+				"Grid row line 4 has the name 'areaB-end'."
+			);
+			isnot(grid.rows.lines[3].names.indexOf("areaC-end"), -1,
+				"Grid row line 4 has the name 'areaC-end'."
+			);
+			
+			// test names of all the column lines
+			isnot(grid.cols.lines[0].names.indexOf("areaA-start"), -1,
+				"Grid column line 1 has the name 'areaA-start'."
+			);
+			isnot(grid.cols.lines[0].names.indexOf("areaB-start"), -1,
+				"Grid column line 1 has the name 'areaB-start'."
+			);
+			
+			isnot(grid.cols.lines[1].names.indexOf("areaB-end"), -1,
+				"Grid column line 2 has the name 'areaB-end'."
+			);
+			isnot(grid.cols.lines[1].names.indexOf("areaC-start"), -1,
+				"Grid column line 2 has the name 'areaC-start'."
+			);
+			
+			isnot(grid.cols.lines[2].names.indexOf("areaA-end"), -1,
+				"Grid column line 3 has the name 'areaA-end'."
+			);
+			
+			isnot(grid.cols.lines[3].names.indexOf("areaC-end"), -1,
+				"Grid column line 4 has the name 'areaC-end'."
+			);
+		}
+	}
+
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper" class="wrapper">
+		<div id="boxA" class="box a">A</div>
+		<div id="boxB" class="box b">B</div>
+		<div id="boxC" class="box c">C</div>
+	</div>
+
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_fragmentation.html b/dom/grid/test/chrome/test_grid_fragmentation.html
new file mode 100644
index 000000000..cec03b12c
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_fragmentation.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: Fragmentation of height:auto grid, not top-of-page</title>
+  <link rel="author" title="Mats Palmgren" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1144096">
+  <link rel="help" href="https://drafts.csswg.org/css-grid/#pagination">
+  <link rel="match" href="grid-fragmentation-001-ref.html">
+
+  <script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+
+  <style type="text/css">
+html,body {
+    color:black; background-color:white; font-size:16px; padding:0; margin:0;
+}
+body { overflow:hidden; }
+
+.columns {
+  position:relative;
+     -moz-columns: 5;
+      -ms-columns: 5;
+  -webkit-columns: 5;
+          columns: 5;
+     -moz-column-fill: auto;
+      -ms-column-fill: auto;
+  -webkit-column-fill: auto;
+          column-fill: auto;
+  border: 2px dashed;
+  margin-bottom: 5px;
+}
+
+.grid {
+  display: grid;
+  grid-template-columns: 30px 30px 30px;
+  grid-auto-rows: 50px;
+  grid-gap: 12px;
+  border:5px solid;
+  align-content: start;
+}
+span { background:lime; border:1px solid black; }
+x { display:block; height:20px; }
+
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	var wrapper = document.getElementById("wrapper");
+	var fragments = wrapper.getGridFragments();
+	
+	// test fragments of the grid
+	is(fragments.length, 2, "Grid is split into two fragments.");
+	
+	if (fragments.length == 2) {
+		var grid0 = fragments[0];
+		var grid1 = fragments[1];
+	
+		// test that both fragments have one row track and two lines
+		is(grid0.rows.tracks.length, 1, "Fragment 0 has one row track.");
+		is(grid0.rows.lines.length, 2, "Fragment 0 has two row lines.");
+		is(grid1.rows.tracks.length, 1, "Fragment 1 has one row track.");
+		is(grid1.rows.lines.length, 2, "Fragment 1 has two row lines.");
+	}
+	
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+<div class="columns" style="height: 100px/*fragmentainer ends in the last row*/">
+<div style="padding-top:10px; background:grey">
+<div id="wrapper" class="grid">
+<span style="grid-row:span 2"><x></x></span>
+<span style="height:60px; background:cyan"><x></x></span>
+<span style="align-self:end; background:pink"><x></x></span>
+<span style="grid-row:1; height:60px"><x></x></span>
+</div></div></div>
+
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_implicit.html b/dom/grid/test/chrome/test_grid_implicit.html
new file mode 100644
index 000000000..c7782e0e5
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_implicit.html
@@ -0,0 +1,250 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	grid-gap: 10px;
+	grid-auto-columns: 20px;
+	grid-auto-rows: 20px;
+	background-color: #f00;
+}
+
+.template1 {
+	grid-template-columns: 100px 50px 100px;
+	grid-template-rows: 50px [areaD-start middle] 50px [areaD-end];
+	grid-template-areas: "areaA areaA ....."
+						 "..... areaC areaC";
+}
+
+.template2 {
+	grid-template-areas: "..... areaA ......";
+    grid-template-columns: [areaA-start] 50px 50px 50px;
+}
+
+.template3 {
+	grid-template-columns: [areaA-start areaB-end areaC-end areaD-start] 50px [areaA-end areaB-start areaC-start areaD-end];
+	grid-template-rows: [areaA-end areaB-start areaC-end] 50px [areaA-start areaB-end areaC-start];
+}
+
+.box {
+	background-color: #444;
+	color: #fff;
+}
+.a {
+	grid-area: areaA;
+}
+.b {
+	grid-row: span got-this-name-implicitly / 2;
+	grid-column: areaA-end / span 2;
+}
+.c {
+	grid-area: areaC;
+}
+.d {
+	grid-area: areaD;
+}
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	// test the first grid wrapper
+	let wrapper = document.getElementById("wrapper1");
+	let grid = wrapper.getGridFragments()[0];
+	
+	// test column and row line counts
+	is(grid.cols.lines.length, 6,
+		"Grid.cols.lines property has length that respects implicit expansion."
+	);
+	is(grid.rows.lines.length, 4,
+		"Grid.rows.lines property has length that respects implicit expansion."
+	);
+
+	if ((grid.cols.lines.length == 6) &&
+	    (grid.rows.lines.length == 4)) {
+
+		// test explicit / implicit lines
+		is(grid.cols.lines[0].type, "explicit", "Grid column line 1 is explicit.");
+		is(grid.cols.lines[4].type, "implicit", "Grid column line 5 is implicit.");
+		is(grid.cols.lines[5].type, "implicit", "Grid column line 6 is implicit.");
+		
+		is(grid.rows.lines[0].type, "implicit", "Grid row line 1 is implicit.");
+		is(grid.rows.lines[1].type, "explicit", "Grid row line 2 is explicit.");
+		is(grid.rows.lines[3].type, "explicit", "Grid row line 4 is explicit.");
+		
+		// test that row line 1 gets the name forced on it by placement of item B
+		todo_isnot(grid.rows.lines[0].names.indexOf("got-this-name-implicitly"), -1,
+			"Grid row line 1 has the name 'got-this-name-implicitly'."
+		);
+		
+		// test that row line 3 gets its explicit name
+		isnot(grid.rows.lines[2].names.indexOf("middle"), -1,
+			"Grid row line 3 has the name 'middle'."
+		);
+		
+		// test the names of the implicit column lines that were created for area 'areaD'
+		isnot(grid.cols.lines[4].names.indexOf("areaD-start"), -1,
+			"Grid column line 5 has the name 'areaD-start'."
+		);
+		isnot(grid.cols.lines[5].names.indexOf("areaD-end"), -1,
+			"Grid column line 6 has the name 'areaD-end'."
+		);
+	}
+
+	// test column and row track counts
+	is(grid.cols.tracks.length, 5,
+		"Grid.cols.tracks property has length that respects implicit expansion."
+	);
+	is(grid.rows.tracks.length, 3,
+		"Grid.rows.tracks property has length that respects implicit expansion."
+	);
+
+	if ((grid.cols.tracks.length == 5) &&
+	    (grid.rows.tracks.length == 3)) {
+
+		// test explicit / implicit tracks
+		is(grid.cols.tracks[0].type, "explicit", "Grid column track 1 is explicit.");
+		is(grid.cols.tracks[3].type, "implicit", "Grid column track 4 is implicit.");
+		is(grid.cols.tracks[4].type, "implicit", "Grid column track 5 is implicit.");
+
+		is(grid.rows.tracks[0].type, "implicit", "Grid row track 1 is implicit.");
+		is(grid.rows.tracks[1].type, "explicit", "Grid row track 2 is explicit.");
+		is(grid.rows.tracks[2].type, "explicit", "Grid row track 3 is explicit.");
+	}
+
+	// test area count
+	is(grid.areas.length, 3,
+		"Grid.areas property has length that respects implicit expansion."
+	);
+
+	for (var i = 0; i < grid.areas.length; i++) {
+		var area = grid.areas[i];
+		if (area.name == "areaD") {
+			is(area.type, "implicit", area.name + " is implicit.");
+
+			// test lines of implicit areas
+			is(area.rowStart, 3, area.name + " has start row line of 3.");
+			is(area.rowEnd, 4, area.name + " has end row line of 4.");
+			is(area.columnStart, 5, area.name + " has start column line of 5.");
+			is(area.columnEnd, 6, area.name + " has end column line of 6.");
+		} else {
+			is(area.type, "explicit", area.name + " is explicit.");
+		}
+	}
+	
+	
+	// test the second grid wrapper
+	wrapper = document.getElementById("wrapper2");
+	grid = wrapper.getGridFragments()[0];
+	
+	// test column and row line counts
+	is(grid.cols.lines.length, 4,
+		"Grid.cols.lines property doesn't expand due to an explicit line declaration."
+	);
+	is(grid.rows.lines.length, 2,
+		"Grid.rows.lines property has length that respects implicit expansion."
+	);
+	
+	// test area count
+	is(grid.areas.length, 1,
+		"Grid.areas property has length that respects implicit expansion."
+	);
+	
+	for (var i = 0; i < grid.areas.length; i++) {
+		var area = grid.areas[i];
+		if (area.name == "areaA") {
+			is(area.type, "implicit", area.name + " is implicit.");
+
+			// test lines of implicit areas
+			is(area.rowStart, 1, area.name + " has start row line of 1.");
+			is(area.rowEnd, 2, area.name + " has end row line of 2.");
+			is(area.columnStart, 1, area.name + " has start column line of 1.");
+			is(area.columnEnd, 3, area.name + " has end column line of 3.");
+		}
+	}
+	
+	
+	// test the third grid wrapper
+	wrapper = document.getElementById("wrapper3");
+	grid = wrapper.getGridFragments()[0];
+	
+	// test column and row line counts
+	is(grid.cols.lines.length, 2,
+		"Grid.cols.lines property doesn't expand due to an explicit line declaration."
+	);
+	is(grid.rows.lines.length, 2,
+		"Grid.rows.lines property doesn't expand due to an explicit line declaration."
+	);
+	
+	if (grid.cols.lines.length == 2 && grid.rows.lines.length == 2) {
+		// check that areaC gets both the explicit line names and the implicit line names
+		isnot(grid.cols.lines[0].names.indexOf("areaC-start"), -1,
+			"Grid row line 1 has the name 'areaC-start'."
+		);
+		
+		isnot(grid.cols.lines[0].names.indexOf("areaC-end"), -1,
+			"Grid row line 1 has the name 'areaC-end'."
+		);
+		
+		isnot(grid.cols.lines[1].names.indexOf("areaC-start"), -1,
+			"Grid row line 2 has the name 'areaC-start'."
+		);
+		
+		isnot(grid.cols.lines[1].names.indexOf("areaC-end"), -1,
+			"Grid row line 2 has the name 'areaC-end'."
+		);
+	}
+	
+	// test area count
+	is(grid.areas.length, 4,
+		"Grid.areas property reports 4 areas."
+	);
+	
+	for (var i = 0; i < grid.areas.length; i++) {
+		var area = grid.areas[i];
+		if (area.name == "areaC") {
+			// test lines of implicit area
+			is(area.rowStart, 1, area.name + " has start row line of 1.");
+			is(area.rowEnd, 2, area.name + " has end row line of 2.");
+			is(area.columnStart, 1, area.name + " has start column line of 1.");
+			is(area.columnEnd, 2, area.name + " has end column line of 2.");
+		}
+	}
+
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper1" class="wrapper template1">
+		<div id="boxA" class="box a">A</div>
+		<div id="boxB" class="box b">B</div>
+		<div id="boxC" class="box c">C</div>
+		<div id="boxD" class="box d">D</div>
+	</div>
+	
+	<br/>
+	
+	<div id="wrapper2" class="wrapper template2">
+		<div id="boxA" class="box a">A</div>
+	</div>
+	
+	<br/>
+	
+	<div id="wrapper3" class="wrapper template3">
+		<div id="boxC" class="box c">C</div>
+	</div>
+
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_lines.html b/dom/grid/test/chrome/test_grid_lines.html
new file mode 100644
index 000000000..3f98f3ca0
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_lines.html
@@ -0,0 +1,117 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	width: 400px;
+	grid-gap: 10px;
+	grid-template-columns: 50px [first] repeat(3, [divider] 100px) [last];
+	grid-template-rows: [top1] repeat(1, [top2] 50px) [bot];
+	background-color: #f00;
+}
+.box {
+	background-color: #444;
+	color: #fff;
+}
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	var wrapper = document.getElementById("wrapper");
+	var grid = wrapper.getGridFragments()[0];
+	
+	// test property existence
+	isnot(typeof(grid.cols.lines), "undefined", "Grid.cols.lines property exists.");
+	
+	if (typeof(grid.cols.lines) != "undefined") {
+		// test column line count
+		is(grid.cols.lines.length, 5,
+			"Grid.cols.lines property has length that matches grid-template-columns."
+		);
+	
+		if (grid.cols.lines.length == 5) {
+			// test column line position
+			is(grid.cols.lines[1].start, 50, "Grid column line 2 position is as expected.");
+
+			// test column line width
+			is(grid.cols.lines[1].breadth, 10, "Grid column line 2 width is as expected.");
+
+			// test column line number
+			is(grid.cols.lines[3].number, 4, "Grid column line 4 number is as expected.");
+
+			// test column line names
+			is(grid.cols.lines[0].names.length, 0, "Grid column line 1 has no names.");
+			
+			is(grid.cols.lines[1].names.length, 2, "Grid column line 2 has 2 names.");
+			isnot(grid.cols.lines[1].names.indexOf("first"), -1,
+				"Grid column line 2 has the name 'first'."
+			);
+			isnot(grid.cols.lines[1].names.indexOf("divider"), -1,
+				"Grid column line 2 has the name 'divider'."
+			);
+			
+			is(grid.cols.lines[4].names.length, 1, "Grid column line 5 has 1 name.");
+			isnot(grid.cols.lines[4].names.indexOf("last"), -1,
+				"Grid column line 5 has the name 'last'."
+			);
+		}
+	}
+	
+	// test property existence
+	isnot(typeof(grid.rows.lines), "undefined", "Grid.rows.lines property exists.");
+	
+	if (typeof(grid.rows.lines) != "undefined") {
+		// test column line count
+		is(grid.rows.lines.length, 3,
+			"Grid.rows.lines property has length that matches grid-template-rows."
+		);
+	
+		if (grid.rows.lines.length == 3) {
+			// test row line names
+			is(grid.rows.lines[0].names.length, 2, "Grid row line 1 has 2 names.");
+			isnot(grid.rows.lines[0].names.indexOf("top1"), -1,
+				"Grid row line 1 has the name 'top1'."
+			);
+			isnot(grid.rows.lines[0].names.indexOf("top2"), -1,
+				"Grid row line 1 has the name 'top2'."
+			);
+			
+			is(grid.rows.lines[1].names.length, 1, "Grid row line 2 has 1 name.");
+			isnot(grid.rows.lines[1].names.indexOf("bot"), -1,
+				"Grid row line 2 has the name 'bot'."
+			);
+			
+			is(grid.rows.lines[2].names.length, 0, "Grid row line 3 has no names.");
+		}
+	}
+	
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper" class="wrapper">
+		<div id="boxA" class="box a">A</div>
+		<div id="boxB" class="box b">B</div>
+		<div id="boxC" class="box c">C</div>
+		<div class="box d">D</div>
+		<div class="box e">E</div>
+		<div class="box f">F</div>
+		<div class="box g">G</div>
+		<div class="box h">H</div>
+	</div>
+	
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_object.html b/dom/grid/test/chrome/test_grid_object.html
new file mode 100644
index 000000000..b68152b61
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_object.html
@@ -0,0 +1,69 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	width: 400px;
+	grid-gap: 10px;
+	grid-template-columns: 100px 1fr 1fr 100px;
+	background-color: #f00;
+}
+.box {
+	background-color: #444;
+	color: #fff;
+}
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	var wrapper = document.getElementById("wrapper");
+	var boxA = document.getElementById("boxA");
+	
+	// test function existence
+	is(typeof(wrapper.getGridFragments), "function",
+		"getGridFragments function exists."
+	);
+	
+	// test that display:grid elements have grids and display:block elements don't	
+	is(boxA.getGridFragments().length, 0, "No grid on display:block styled objects.");
+	is(wrapper.getGridFragments().length, 1,
+		"One grid on an un-fragmented display:grid styled object."
+	);
+	
+	if (wrapper.getGridFragments().length == 1) {
+		var grid = wrapper.getGridFragments()[0];
+		
+		isnot(typeof(grid.cols), "undefined", "Grid.cols property exists.");
+		isnot(typeof(grid.rows), "undefined", "Grid.rows property exists.");
+	}
+	
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper" class="wrapper">
+		<div id="boxA" class="box a">A</div>
+		<div class="box b">B</div>
+		<div class="box c">C</div>
+		<div class="box d">D</div>
+		<div class="box e">E</div>
+		<div class="box f">F</div>
+		<div class="box g">G</div>
+		<div class="box h">H</div>
+	</div>
+	
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_repeats.html b/dom/grid/test/chrome/test_grid_repeats.html
new file mode 100644
index 000000000..34ae7da4e
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_repeats.html
@@ -0,0 +1,358 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	width: 600px;
+	grid-gap: 0px;
+	background-color: #f00;
+}
+.grid1 {
+	grid-template-columns: 50px 0px repeat(auto-fit, 100px);
+}
+.grid2 {
+	grid-template-columns: 50px 0px [real-before] repeat(auto-fit, [before] 100px [after]) [real-after] 0px [final];
+}
+.grid3 {
+	grid-template-columns: repeat(3, 66px) [real-before] repeat(auto-fit, [before] 100px [after]) [real-after];
+}
+.grid4 {
+	grid-template-columns: repeat(2, 100px) repeat(auto-fill, 50px);
+}
+.grid5 {
+	grid-template-columns: [real-before] repeat(auto-fit, [before] 100px [after]) [real-after];
+}
+.grid6 {
+	grid-template-columns: [first] 0px [real-before] repeat(auto-fit, [before] 100px [after]) [real-after];
+}
+.grid7 {
+	grid-template-columns: [real-before] repeat(auto-fit, [before] 100px [after]) [real-after] 0px [final];
+}
+.grid8 {
+	grid-template-columns: [real-before] repeat(auto-fit, [before] 1000px [after]) [real-after];
+}
+.grid9 {
+	grid-template-columns: [real-before] repeat(auto-fit, 100px [after]) [real-after];
+}
+.grid10 {
+	grid-template-columns: [real-before] repeat(auto-fit, [before] 100px) [real-after];
+}
+.box {
+	background-color: #444;
+	color: #fff;
+}
+.a {
+	grid-column: auto;
+}
+.b {
+	grid-column: 4;
+}
+.c {
+	grid-column: 6;
+}
+.d {
+	grid-column: 7;
+}
+.e {
+	grid-column: 5;
+}
+
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function testLines(elementName, grid, expectedValues) {
+	for (let i = 0; i < grid.cols.lines.length; i++) {
+		is(grid.cols.lines[i].number, (i + 1), elementName + " line " + (i + 1) + " has expected number.");
+		is(grid.cols.lines[i].start, expectedValues[i].start, elementName + " line " + (i + 1) + " has expected start.");
+		is(grid.cols.lines[i].breadth, 0, elementName + " line " + (i + 1) + " has zero breadth.");
+		is(grid.cols.lines[i].names + "", expectedValues[i].names, elementName + " line " + (i + 1) + " has expected names.");
+	}
+}
+
+function runTests() {
+	let wrapper = document.getElementById("wrapper1");
+	let grid = wrapper.getGridFragments()[0];
+
+	// test auto-fit count
+	is(grid.cols.tracks.length, 7, "Grid column track array reports removed auto-fit columns.");
+
+	// test resolved value of grid-template-columns
+	let templateColumnsText = getComputedStyle(wrapper).gridTemplateColumns;
+	is(templateColumnsText, "50px 0px 0px 100px 0px 0px 0px",
+		"Resolved value of grid-template-columns reports removed auto-fits as '0px'.");
+
+	// test starts, breadths, and states
+	let expectedValues = [
+		{ "start": 0,
+		  "breadth": 50,
+		  "state": "static" },
+		{ "start": 50,
+		  "breadth": 0,
+		  "state": "static" },
+		{ "start": 50,
+		  "breadth": 0,
+		  "state": "removed" },
+		{ "start": 50,
+		  "breadth": 100,
+		  "state": "repeat" },
+		{ "start": 150,
+		  "breadth": 0,
+		  "state": "removed" },
+		{ "start": 150,
+		  "breadth": 0,
+		  "state": "removed" },
+		{ "start": 150,
+		  "breadth": 0,
+		  "state": "removed" },
+	];
+	for (let i = 0; i < grid.cols.tracks.length; i++) {
+		is(grid.cols.tracks[i].start, expectedValues[i].start, "Column " + (i + 1) + " has expected start.");
+		is(grid.cols.tracks[i].breadth, expectedValues[i].breadth, "Column " + (i + 1) + " has expected breadth.");
+		is(grid.cols.tracks[i].state, expectedValues[i].state, "Column " + (i + 1) + " has expected state.");
+	}
+
+
+	wrapper = document.getElementById("wrapper2");
+	grid = wrapper.getGridFragments()[0];
+
+	// test auto-fit count
+	is(grid.cols.lines.length, 9, "Grid column line array reports removed auto-fit columns.");
+
+	// test resolved value of grid-template-columns
+	templateColumnsText = getComputedStyle(wrapper).gridTemplateColumns;
+	is(templateColumnsText, "50px 0px [real-before before] 0px [after before] 100px [after before] 0px [after before] 100px [after before] 0px [after real-after] 0px [final]",
+		"Resolved value of grid-template-columns reports lines for removed tracks.");
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "" },
+		{ "start": 50,
+		  "names": "" },
+		{ "start": 50,
+		  "names": "real-before,before" },
+		{ "start": 50,
+		  "names": "after,before" },
+		{ "start": 150,
+		  "names": "after,before" },
+		{ "start": 150,
+		  "names": "after,before" },
+		{ "start": 250,
+		  "names": "after,before" },
+		{ "start": 250,
+		  "names": "after,real-after" },
+		{ "start": 250,
+		  "names": "final" },
+	];
+	testLines("wrapper2", grid, expectedValues);
+
+
+	wrapper = document.getElementById("wrapper3");
+	grid = wrapper.getGridFragments()[0];
+
+	// test resolved value of grid-template-columns
+	templateColumnsText = getComputedStyle(wrapper).gridTemplateColumns;
+	is(templateColumnsText, "66px 66px 66px [real-before before] 100px [after before] 0px [after before] 100px [after before] 100px [after real-after]",
+		"Resolved value of grid-template-columns reports lines for removed tracks.");
+
+
+	wrapper = document.getElementById("wrapper4");
+	grid = wrapper.getGridFragments()[0];
+
+	// test auto-fill count of tracks
+	is(grid.cols.tracks.length, 10, "Grid column track array respects auto-fill columns.");
+
+	if (grid.cols.tracks.length == 10) {
+		// test for static and repeat
+		is(grid.cols.tracks[1].state, "static", "Grid column track 2 is marked as static.");
+		is(grid.cols.tracks[2].state, "repeat", "Grid column track 3 is marked as repeat.");
+	}
+
+
+	wrapper = document.getElementById("wrapper5");
+	grid = wrapper.getGridFragments()[0];
+
+	// test resolved value of grid-template-columns
+	templateColumnsText = getComputedStyle(wrapper).gridTemplateColumns;
+	is(templateColumnsText, "[real-before before] 0px [after before] 0px [after before] 0px [after before] 0px [after before] 0px [after before] 0px [after real-after]", "Resolved value of grid-template-columns no longer lists 'none' when all auto-fit tracks are empty.");
+
+
+	wrapper = document.getElementById("wrapper6");
+	grid = wrapper.getGridFragments()[0];
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "first" },
+		{ "start": 0,
+		  "names": "real-before,before" },
+		{ "start": 0,
+		  "names": "after,before" },
+		{ "start": 0,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,real-after" },
+	];
+	testLines("wrapper6", grid, expectedValues);
+
+
+	wrapper = document.getElementById("wrapper7");
+	grid = wrapper.getGridFragments()[0];
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "real-before,before" },
+		{ "start": 0,
+		  "names": "after,before" },
+		{ "start": 0,
+		  "names": "after,before" },
+		{ "start": 0,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,before" },
+		{ "start": 100,
+		  "names": "after,real-after" },
+		{ "start": 100,
+		  "names": "final" },
+	];
+	testLines("wrapper7", grid, expectedValues);
+
+
+	wrapper = document.getElementById("wrapper8");
+	grid = wrapper.getGridFragments()[0];
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "real-before,before" },
+		{ "start": 0,
+		  "names": "after,real-after" },
+	];
+	testLines("wrapper8", grid, expectedValues);
+
+
+	wrapper = document.getElementById("wrapper9");
+	grid = wrapper.getGridFragments()[0];
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "real-before" },
+		{ "start": 0,
+		  "names": "after" },
+		{ "start": 0,
+		  "names": "after" },
+		{ "start": 0,
+		  "names": "after" },
+		{ "start": 100,
+		  "names": "after" },
+		{ "start": 200,
+		  "names": "after" },
+		{ "start": 200,
+		  "names": "after,real-after" },
+	];
+	testLines("wrapper9", grid, expectedValues);
+
+
+	wrapper = document.getElementById("wrapper10");
+	grid = wrapper.getGridFragments()[0];
+
+	// test starts and names
+	expectedValues = [
+		{ "start": 0,
+		  "names": "real-before,before" },
+		{ "start": 0,
+		  "names": "before" },
+		{ "start": 0,
+		  "names": "before" },
+		{ "start": 0,
+		  "names": "before" },
+		{ "start": 100,
+		  "names": "before" },
+		{ "start": 200,
+		  "names": "before" },
+		{ "start": 200,
+		  "names": "real-after" },
+	];
+	testLines("wrapper10", grid, expectedValues);
+
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper1" class="wrapper grid1">
+		<div id="boxB" class="box b">B</div>
+	</div>
+
+	<br/>
+	<div id="wrapper2" class="wrapper grid2">
+		<div id="boxB" class="box b">B</div>
+		<div id="boxC" class="box c">C</div>
+	</div>
+
+	<br/>
+	<div id="wrapper3" class="wrapper grid3">
+		<div id="boxB" class="box b">B</div>
+		<div id="boxC" class="box c">C</div>
+		<div id="boxD" class="box d">D</div>
+	</div>
+
+	<br/>
+	<div id="wrapper4" class="wrapper grid4">
+		<div id="boxA" class="box a">A</div>
+	</div>
+
+	<br/>
+	<div id="wrapper5" class="wrapper grid5">
+	</div>
+
+	<br/>
+	<div id="wrapper6" class="wrapper grid6">
+		<div id="boxB" class="box b">B</div>
+	</div>
+
+	<br/>
+	<div id="wrapper7" class="wrapper grid7">
+		<div id="boxB" class="box b">B</div>
+	</div>
+
+	<br/>
+	<div id="wrapper8" class="wrapper grid8">
+	</div>
+
+	<br/>
+	<div id="wrapper9" class="wrapper grid9">
+		<div id="boxB" class="box b">B</div>
+		<div id="boxE" class="box e">E</div>
+	</div>
+
+	<br/>
+	<div id="wrapper10" class="wrapper grid10">
+		<div id="boxB" class="box b">B</div>
+		<div id="boxE" class="box e">E</div>
+	</div>
+
+</body>
+</html>
diff --git a/dom/grid/test/chrome/test_grid_tracks.html b/dom/grid/test/chrome/test_grid_tracks.html
new file mode 100644
index 000000000..9b58cd50d
--- /dev/null
+++ b/dom/grid/test/chrome/test_grid_tracks.html
@@ -0,0 +1,85 @@
+<!doctype html>
+<html>
+<head>
+<meta charset="utf-8">
+<script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+<style>
+body {
+	margin: 40px;
+}
+.wrapper {
+	display: grid;
+	width: 400px;
+	grid-gap: 10px;
+	grid-template-columns: 100px 1fr 1fr 100px;
+	background-color: #f00;
+}
+.box {
+	background-color: #444;
+	color: #fff;
+}
+</style>
+
+<script>
+'use strict';
+
+SimpleTest.waitForExplicitFinish();
+
+function runTests() {
+	var wrapper = document.getElementById("wrapper");
+	var grid = wrapper.getGridFragments()[0];
+	var boxA = document.getElementById("boxA");
+	var boxB = document.getElementById("boxB");
+	
+	// test property existence
+	isnot(typeof(grid.cols.tracks), "undefined", "Grid.cols.tracks property exists.");
+	isnot(typeof(grid.rows.tracks), "undefined", "Grid.rows.tracks property exists.");
+	
+	if ((typeof(grid.cols.tracks) != "undefined") &&
+		(typeof(grid.rows.tracks) != "undefined")) {
+		// test column and row track counts
+		is(grid.cols.tracks.length, 4,
+			"Grid.cols.tracks property has length that matches grid-template-columns."
+		);
+		is(grid.rows.tracks.length, 2,
+			"Grid.rows.tracks property has length that matches content."
+		);
+	
+		if((grid.cols.tracks.length == 4) &&
+		   (grid.rows.tracks.length == 2)) {
+			// test column track position
+			is(grid.cols.tracks[1].start, 110, "Grid column track 2 position is as expected.");
+	
+			// test column track width
+			is(grid.cols.tracks[0].breadth, boxA.offsetWidth,
+				"Grid column track width (fixed size) matches item width."
+			);
+			is(grid.cols.tracks[1].breadth, boxB.offsetWidth,
+				"Grid column track width (flexible size) matches item width."
+			);
+			is(grid.cols.tracks[1].breadth, grid.cols.tracks[2].breadth,
+				"Grid column track widths with equal proportion flexible size actually are same size."
+			);
+		}
+	}
+	
+	SimpleTest.finish();
+}
+</script>
+</head>
+<body onLoad="runTests();">
+
+	<div id="wrapper" class="wrapper">
+		<div id="boxA" class="box a">A</div>
+		<div id="boxB" class="box b">B</div>
+		<div class="box c">C</div>
+		<div class="box d">D</div>
+		<div class="box e">E</div>
+		<div class="box f">F</div>
+		<div class="box g">G</div>
+		<div class="box h">H</div>
+	</div>
+	
+</body>
+</html>