Remove dartc optimizing backend.

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

Index: dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
diff --git a/dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java b/dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
index 23933924df30a9116d2d100d4367bd68b43d4250..b4723a4a9b82057db82f911a4c0c1049be062407 100644
--- a/dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
+++ b/dart/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
@@ -6,7 +6,6 @@ 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;
@@ -47,10 +46,6 @@ public class DefaultCompilerConfiguration implements CompilerConfiguration {
     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();
     }
@@ -134,11 +129,6 @@ public class DefaultCompilerConfiguration implements CompilerConfiguration {
   }
 
   @Override
-  public boolean shouldOptimize() {
-    return compilerOptions.shouldOptimize();
-  }
-
-  @Override
   public CompilerMetrics getCompilerMetrics() {
     return compilerMetrics;
   }