Avoid calling slice in self-hosted code. DiD

This time without unrelated/incomplete pluralforms junk.

1 files changed, 21 insertions, 3 deletions

diff --git a/js/src/builtin/Intl.js b/js/src/builtin/Intl.js
index 493062c1c..509168d7a 100644
--- a/js/src/builtin/Intl.js
+++ b/js/src/builtin/Intl.js
@@ -432,7 +432,7 @@ function CanonicalizeLanguageTag(locale) {
         subtags[i] = subtag;
         i++;
     }
-    var normal = callFunction(std_Array_join, callFunction(std_Array_slice, subtags, 0, i), "-");
+    var normal = ArrayJoinRange(subtags, "-", 0, i);
 
     // Extension sequences are sorted by their singleton characters.
     // "u-ca-chinese-t-zh-latn" -> "t-zh-latn-u-ca-chinese"
@@ -442,7 +442,7 @@ function CanonicalizeLanguageTag(locale) {
         i++;
         while (i < subtags.length && subtags[i].length > 1)
             i++;
-        var extension = callFunction(std_Array_join, callFunction(std_Array_slice, subtags, extensionStart, i), "-");
+        var extension = ArrayJoinRange(subtags, "-", extensionStart, i);
         callFunction(std_Array_push, extensions, extension);
     }
     callFunction(std_Array_sort, extensions);
@@ -450,7 +450,7 @@ function CanonicalizeLanguageTag(locale) {
     // Private use sequences are left as is. "x-private"
     var privateUse = "";
     if (i < subtags.length)
-        privateUse = callFunction(std_Array_join, callFunction(std_Array_slice, subtags, i), "-");
+        privateUse = ArrayJoinRange(subtags, "-", i);
 
     // Put everything back together.
     var canonical = normal;
@@ -467,6 +467,24 @@ function CanonicalizeLanguageTag(locale) {
     return canonical;
 }
 
+/**
+ * Joins the array elements in the given range with the supplied separator.
+ */
+function ArrayJoinRange(array, separator, from, to = array.length) {
+    assert(typeof separator === "string", "|separator| is a string value");
+    assert(typeof from === "number", "|from| is a number value");
+    assert(typeof to === "number", "|to| is a number value");
+    assert(0 <= from && from <= to && to <= array.length, "|from| and |to| form a valid range");
+
+    if (from === to)
+        return "";
+
+    var result = array[from];
+    for (var i = from + 1; i < to; i++) {
+        result += separator + array[i];
+    }
+    return result;
+}
 
 function localeContainsNoUnicodeExtensions(locale) {
     // No "-u-", no possible Unicode extension.