Fix performance regression after adding inlining support for operators, [], and []=.

sdk/lib/_internal/compiler/implementation/ssa/codegen.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 ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 612 matching lines @@
     if (isGeneratingExpression) {
       visitExpression(instruction);
     } else {
       visitStatement(instruction);
     }
   }
 
   void use(HInstruction argument) {
     if (isGenerateAtUseSite(argument)) {
       visitExpression(argument);
-    } else if (argument is HCheck && argument.isControlFlow()) {
-      // A [HCheck] that has control flow can never be used as an
-      // expression and may not have a name. Therefore we just use the
-      // checked instruction.
+    } else if (argument is HCheck && !variableNames.hasName(argument)) {
       HCheck check = argument;
       use(check.checkedInput);
     } else {
       push(new js.VariableUse(variableNames.getName(argument)));
     }
   }
 
   visit(HInstruction node) {
     node.accept(this);
   }
@@ skipping 2315 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }