Optimize DDC private library files.

pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart

 // Copyright (c) 2012, 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 file for dart:core classes.
 import "dart:_internal" as _symbol_dev;
 import 'dart:_interceptors';
 import 'dart:_js_helper'
     show
         patch,
         checkInt,
         getRuntimeType,
         getTraceFromException,
         jsonEncodeNative,
         JsLinkedHashMap,
         JSSyntaxRegExp,
         NoInline,
+        notNull,
+        nullCheck,
         objectHashCode,
         Primitives,
         stringJoinUnchecked;
 
 import 'dart:_foreign_helper' show JS;
 
 import 'dart:_native_typed_data' show NativeUint8List;
 
 String _symbolToString(Symbol symbol) => _symbol_dev.Symbol.getName(symbol);
 
@@ skipping 284 matching lines @@
   }
 
   @patch
   static int _now() => Primitives.timerTicks();
 }
 
 // Patch for List implementation.
 @patch
 class List<E> {
   @patch
-  factory List([int length]) {
+  factory List([int _length]) {
     dynamic list;
-    if (length == null) {
+    if (_length == null) {
       list = JS('', '[]');
     } else {
-      // Explicit type test is necessary to guard against JavaScript conversions
-      // in unchecked mode.
-      if ((length is! int) || (length < 0)) {
+      @notNull
+      var length = _length;
+      if (length < 0) {
         throw new ArgumentError(
             "Length must be a non-negative integer: $length");
       }
       list = JSArray.markFixedList(JS('', 'new Array(#)', length));
     }
     return new JSArray<E>.of(list);
   }
 
   @patch
   factory List.filled(int length, E fill, {bool growable: true}) {
     List<E> result = new List<E>(length);
     if (length != 0 && fill != null) {
-      for (int i = 0; i < result.length; i++) {
+      @notNull
+      var length = result.length;
+      for (int i = 0; i < length; i++) {
         result[i] = fill;
       }
     }
     if (growable) return result;
-    return makeListFixedLength/*<E>*/(result);
+    return makeListFixedLength<E>(result);
   }
 
   @patch
   factory List.from(Iterable elements, {bool growable: true}) {
     List<E> list = new List<E>();
-    for (var e in elements) {
-      list.add(e);
+    // Specialize the copy loop for the case that doesn't need a
+    // runtime check.
+    if (elements is Iterable<E>) {
+      for (var e in elements) {
+        list.add(e);
+      }
+    } else {
+      for (var e in elements) {
+        list.add(e);

[Jennifer Messerly, 2017/08/22 21:54:40]

make `as E` explicit?

I'm thinking of disabling implicit casts in our impl code

[Leaf, 2017/08/23 17:26:13]

Done.

+      }
     }
     if (growable) return list;
     return makeListFixedLength/*<E>*/(list);
   }
 
   @patch
   factory List.unmodifiable(Iterable elements) {
     var result = new List<E>.from(elements, growable: false);
     return makeFixedListUnmodifiable/*<E>*/(result);
   }
@@ skipping 291 matching lines @@
   static StackTrace get current {
     return getTraceFromException(JS('', 'new Error()'));
   }
 }
 
 @patch
 class _ConstantExpressionError {
   @patch
   _throw(error) => throw error;
 }