Optimize length access on all JSIndexable things.

sdk/lib/_internal/compiler/implementation/js_backend/backend.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.
 
 part of js_backend;
 
 typedef void Recompile(Element element);
 
 class ReturnInfo {
   HType returnType;
@@ skipping 638 matching lines @@
   ClassElement jsDoubleClass;
   ClassElement jsFunctionClass;
   ClassElement jsNullClass;
   ClassElement jsBoolClass;
 
   ClassElement jsIndexableClass;
   ClassElement jsMutableArrayClass;
   ClassElement jsFixedArrayClass;
   ClassElement jsExtendableArrayClass;
 
-  Element jsArrayLength;
-  Element jsStringLength;
+  Element jsIndexableLength;
   Element jsArrayRemoveLast;
   Element jsArrayAdd;
   Element jsStringSplit;
   Element jsStringConcat;
   Element jsStringToString;
   Element objectEquals;
 
   ClassElement typeLiteralClass;
   ClassElement mapLiteralClass;
   ClassElement constMapLiteralClass;
@@ skipping 232 matching lines @@
     // TODO(kasperl): Some tests do not define the special JSArray
     // subclasses, so we check to see if they are defined before
     // trying to resolve them.
     if (jsFixedArrayClass != null) {
       jsFixedArrayClass.ensureResolved(compiler);
     }
     if (jsExtendableArrayClass != null) {
       jsExtendableArrayClass.ensureResolved(compiler);
     }
 
+    jsIndexableClass.ensureResolved(compiler);
+    jsIndexableLength = compiler.lookupElementIn(
+        jsIndexableClass, const SourceString('length'));
+    if (jsIndexableLength != null && jsIndexableLength.isAbstractField()) {
+      AbstractFieldElement element = jsIndexableLength;
+      jsIndexableLength = element.getter;
+    }
+
     jsArrayClass.ensureResolved(compiler);
-    jsArrayLength = compiler.lookupElementIn(
-        jsArrayClass, const SourceString('length'));
-    if (jsArrayLength != null && jsArrayLength.isAbstractField()) {
-      AbstractFieldElement element = jsArrayLength;
-      jsArrayLength = element.getter;
-    }
     jsArrayRemoveLast = compiler.lookupElementIn(
         jsArrayClass, const SourceString('removeLast'));
     jsArrayAdd = compiler.lookupElementIn(
         jsArrayClass, const SourceString('add'));
 
     jsStringClass.ensureResolved(compiler);
-    jsStringLength = compiler.lookupElementIn(
-        jsStringClass, const SourceString('length'));
-    if (jsStringLength != null && jsStringLength.isAbstractField()) {
-      AbstractFieldElement element = jsStringLength;
-      jsStringLength = element.getter;
-    }
     jsStringSplit = compiler.lookupElementIn(
         jsStringClass, const SourceString('split'));
     jsStringConcat = compiler.lookupElementIn(
         jsStringClass, const SourceString('concat'));
     jsStringToString = compiler.lookupElementIn(
         jsStringClass, const SourceString('toString'));
 
     for (ClassElement cls in classes) {
       if (cls != null) interceptedClasses.add(cls);
     }
@@ skipping 838 matching lines @@
   ClassElement get constListImplementation => jsArrayClass;
   ClassElement get fixedListImplementation => jsFixedArrayClass;
   ClassElement get growableListImplementation => jsExtendableArrayClass;
   ClassElement get mapImplementation => mapLiteralClass;
   ClassElement get constMapImplementation => constMapLiteralClass;
   ClassElement get functionImplementation => jsFunctionClass;
   ClassElement get typeImplementation => typeLiteralClass;
   ClassElement get boolImplementation => jsBoolClass;
   ClassElement get nullImplementation => jsNullClass;
 }