dart2js cps: Fix bug in pulling of assignments into a var.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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.
 
 library code_generator;
 
 import 'glue.dart';
 
 import '../../closure.dart' show
     ClosureClassElement;
@@ skipping 103 matching lines @@
 
       // Check that node is an assignment to a local variable.
       if (node is! js.ExpressionStatement) break;
       js.ExpressionStatement stmt = node;
       if (stmt.expression is! js.Assignment) break;
       js.Assignment assign = stmt.expression;
       if (assign.leftHandSide is! js.VariableUse) break;
       if (assign.op != null) break; // Compound assignment.
       js.VariableUse use = assign.leftHandSide;
 
+      // Do not touch non-local variables.
+      if (!usedVariableNames.contains(use.name)) break;
+
       // We cannot declare a variable more than once.
       if (!declaredVariables.add(use.name)) break;
 
       js.VariableInitialization jsVariable = new js.VariableInitialization(
         new js.VariableDeclaration(use.name),
         assign.value);
       jsVariables.add(jsVariable);
 
       ++accumulatorIndex;
     }
 
     // If the last statement is a for loop with an initializer expression, try
     // to pull that expression into an initializer as well.
     pullFromForLoop:
     if (accumulatorIndex < accumulator.length &&
         accumulator[accumulatorIndex] is js.For) {
       js.For forLoop = accumulator[accumulatorIndex];
       if (forLoop.init is! js.Assignment) break pullFromForLoop;
       js.Assignment assign = forLoop.init;
       if (assign.leftHandSide is! js.VariableUse) break pullFromForLoop;
       if (assign.op != null) break pullFromForLoop; // Compound assignment.
       js.VariableUse use = assign.leftHandSide;
 
+      // Do not touch non-local variables.
+      if (!usedVariableNames.contains(use.name)) break pullFromForLoop;
+
       // We cannot declare a variable more than once.
       if (!declaredVariables.add(use.name)) break pullFromForLoop;
 
       js.VariableInitialization jsVariable = new js.VariableInitialization(
         new js.VariableDeclaration(use.name),
         assign.value);
       jsVariables.add(jsVariable);
 
       // Remove the initializer from the for loop.
       accumulator[accumulatorIndex] =
@@ skipping 1074 matching lines @@
   void registerDefaultParameterValues(ExecutableElement element) {
     if (element is! FunctionElement) return;
     FunctionElement function = element;
     if (function.isStatic) return; // Defaults are inlined at call sites.
     function.functionSignature.forEachOptionalParameter((param) {
       ConstantValue constant = glue.getDefaultParameterValue(param);
       registry.registerCompileTimeConstant(constant);
     });
   }
 }