Remove backends.

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java
diff --git a/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java
index a3c113fd2be0d340bd0193ad537cbe7ef81ffdcf..446b89e95abb335801720813e423eba2c71e9170 100644
--- a/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java
+++ b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/util/LibraryReferenceFinder.java
@@ -13,7 +13,7 @@
  */
 package com.google.dart.tools.core.internal.util;
 
-import com.google.dart.compiler.backend.js.JavascriptBackend;
+import com.google.dart.tools.core.DartCore;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -197,10 +197,10 @@ public class LibraryReferenceFinder {
       String scriptType = getAttributeValue(scriptTag, "type");
       if (scriptType == null || scriptType.equals("text/javascript")
           || scriptType.equals("application/javascript")) {
-        if (srcLocation.endsWith('.' + JavascriptBackend.EXTENSION_APP_JS)) {
+        if (srcLocation.endsWith('.' + DartCore.EXTENSION_APP_JS)) {
           String fileName = extractFileNameFromSrc(srcLocation);
-          fileName = fileName.substring(0,
-              fileName.length() - JavascriptBackend.EXTENSION_APP_JS.length() - 1);
+          fileName = fileName.substring(0, fileName.length() - DartCore.EXTENSION_APP_JS.length()
+              - 1);
           libraryList.add(fileName);
         }
         // Match the "Generate Optimized Javascript" default extension