Remove dartc optimizing backend.

dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java

 // Copyright (c) 2011, 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.
 
 package com.google.dart.compiler;
 
 import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
 import com.google.dart.compiler.backend.isolate.DartIsolateStubGenerator;
-import com.google.dart.compiler.backend.js.ClosureJsBackend;
 import com.google.dart.compiler.backend.js.JavascriptBackend;
 import com.google.dart.compiler.metrics.CompilerMetrics;
 import com.google.dart.compiler.resolver.CompileTimeConstantAnalyzer;
 import com.google.dart.compiler.resolver.Resolver;
 import com.google.dart.compiler.type.TypeAnalyzer;
 
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ skipping 20 matching lines @@
    */
   public DefaultCompilerConfiguration() {
     this(new JavascriptBackend());
   }
 
   private static Backend selectBackend(CompilerOptions compilerOptions)
       throws FileNotFoundException {
     if (!compilerOptions.getIsolateStubClasses().isEmpty()) {
       return new DartIsolateStubGenerator(compilerOptions.getIsolateStubClasses(),
                                           compilerOptions.getIsolateStubOutputFile());
-    } else if (compilerOptions.shouldOptimize()) {
-      return new ClosureJsBackend(
-          compilerOptions.developerModeChecks(),
-          compilerOptions.generateHumanReadableOutput());
     } else {
       return new JavascriptBackend();
     }
   }
 
   /**
    * A new instance with the specified {@link CompilerOptions}
    * @throws FileNotFoundException
    */
   public DefaultCompilerConfiguration(CompilerOptions compilerOptions)
@@ skipping 63 matching lines @@
   public List<Backend> getBackends() {
     return backends;
   }
 
   @Override
   public boolean developerModeChecks() {
     return compilerOptions.developerModeChecks();
   }
 
   @Override
-  public boolean shouldOptimize() {
-    return compilerOptions.shouldOptimize();
-  }
-
-  @Override
   public CompilerMetrics getCompilerMetrics() {
     return compilerMetrics;
   }
 
   @Override
   public String getJvmMetricOptions() {
     return compilerOptions.getJvmMetricOptions();
   }
 
   @Override
@@ skipping 60 matching lines @@
   @Override
   public CompilerOptions getCompilerOptions() {
     return compilerOptions;
   }
 
   @Override
   public ErrorFormat printErrorFormat() {
     return compilerOptions.printErrorFormat();
   }
 }