Speed up typed *List:fromList constructor, by calling setRange.

runtime/lib/typed_data.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // patch classes for Int8List ..... Float64List and ByteData implementations.
 
 import "dart:_internal";
 import 'dart:math' show Random;
 
 patch class Int8List {
   /* patch */ factory Int8List(int length) {
     return new _Int8Array(length);
   }
 
   /* patch */ factory Int8List.fromList(List<int> elements) {
-    var result = new _Int8Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Int8Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Int8List.view(ByteBuffer buffer,
                                     [int offsetInBytes = 0, int length]) {
     return new _Int8ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Uint8List {
   /* patch */ factory Uint8List(int length) {
     return new _Uint8Array(length);
   }
 
   /* patch */ factory Uint8List.fromList(List<int> elements) {
-    var result = new _Uint8Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Uint8Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Uint8List.view(ByteBuffer buffer,
                                      [int offsetInBytes = 0, int length]) {
     return new _Uint8ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Uint8ClampedList {
   /* patch */ factory Uint8ClampedList(int length) {
     return new _Uint8ClampedArray(length);
   }
 
   /* patch */ factory Uint8ClampedList.fromList(List<int> elements) {
-    var result = new _Uint8ClampedArray(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Uint8ClampedArray(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Uint8ClampedList.view(ByteBuffer buffer,
                                             [int offsetInBytes = 0,
                                              int length]) {
     return new _Uint8ClampedArrayView(buffer, offsetInBytes, length);
   }
 
   bool _isClamped() { return true; }
 }
 
 
 patch class Int16List {
   /* patch */ factory Int16List(int length) {
     return new _Int16Array(length);
   }
 
   /* patch */ factory Int16List.fromList(List<int> elements) {
-    var result = new _Int16Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Int16Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Int16List.view(ByteBuffer buffer,
                                      [int offsetInBytes = 0, int length]) {
     return new _Int16ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Uint16List {
   /* patch */ factory Uint16List(int length) {
     return new _Uint16Array(length);
   }
 
   /* patch */ factory Uint16List.fromList(List<int> elements) {
-    var result = new _Uint16Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Uint16Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Uint16List.view(ByteBuffer buffer,
                                       [int offsetInBytes = 0, int length]) {
     return new _Uint16ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Int32List {
   /* patch */ factory Int32List(int length) {
     return new _Int32Array(length);
   }
 
   /* patch */ factory Int32List.fromList(List<int> elements) {
-    var result = new _Int32Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Int32Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Int32List.view(ByteBuffer buffer,
                                      [int offsetInBytes = 0, int length]) {
     return new _Int32ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Uint32List {
   /* patch */ factory Uint32List(int length) {
     return new _Uint32Array(length);
   }
 
   /* patch */ factory Uint32List.fromList(List<int> elements) {
-    var result = new _Uint32Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Uint32Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Uint32List.view(ByteBuffer buffer,
                                       [int offsetInBytes = 0, int length]) {
     return new _Uint32ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Int64List {
   /* patch */ factory Int64List(int length) {
     return new _Int64Array(length);
   }
 
   /* patch */ factory Int64List.fromList(List<int> elements) {
-    var result = new _Int64Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Int64Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Int64List.view(ByteBuffer buffer,
                                      [int offsetInBytes = 0, int length]) {
     return new _Int64ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Uint64List {
   /* patch */ factory Uint64List(int length) {
     return new _Uint64Array(length);
   }
 
   /* patch */ factory Uint64List.fromList(List<int> elements) {
-    var result = new _Uint64Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Uint64Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Uint64List.view(ByteBuffer buffer,
                                       [int offsetInBytes = 0, int length]) {
     return new _Uint64ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Float32List {
   /* patch */ factory Float32List(int length) {
     return new _Float32Array(length);
   }
 
   /* patch */ factory Float32List.fromList(List<double> elements) {
-    var result = new _Float32Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Float32Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Float32List.view(ByteBuffer buffer,
                                        [int offsetInBytes = 0, int length]) {
     return new _Float32ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Float64List {
   /* patch */ factory Float64List(int length) {
     return new _Float64Array(length);
   }
 
   /* patch */ factory Float64List.fromList(List<double> elements) {
-    var result = new _Float64Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Float64Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Float64List.view(ByteBuffer buffer,
                                        [int offsetInBytes = 0, int length]) {
     return new _Float64ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 patch class Float32x4List {
   /* patch */ factory Float32x4List(int length) {
     return new _Float32x4Array(length);
   }
 
   /* patch */ factory Float32x4List.fromList(List<Float32x4> elements) {
-    var result = new _Float32x4Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Float32x4Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Float32x4List.view(ByteBuffer buffer,
                                          [int offsetInBytes = 0, int length]) {
     return new _Float32x4ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Int32x4List {
   /* patch */ factory Int32x4List(int length) {
     return new _Int32x4Array(length);
   }
 
   /* patch */ factory Int32x4List.fromList(List<Int32x4> elements) {
-    var result = new _Int32x4Array(elements.length);
-    for (int i = 0; i < elements.length; i++) {
-      result[i] = elements[i];
-    }
-    return result;
+    return new _Int32x4Array(elements.length)
+        ..setRange(0, elements.length, elements);
   }
 
   /* patch */ factory Int32x4List.view(ByteBuffer buffer,
                                         [int offsetInBytes = 0, int length]) {
     return new _Int32x4ArrayView(buffer, offsetInBytes, length);
   }
 }
 
 
 patch class Float32x4 {
@@ skipping 3130 matching lines @@
     return value;
   }
   return object;
 }
 
 
 void _throwRangeError(int index, int length) {
   String message = "$index must be in the range [0..$length)";
   throw new RangeError(message);
 }