Remove Compiler and JavaScriptBackend from program_builder and collector.

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

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 4b640d3963490fb01233035fa15c9a2ff6040a24..f655159c43beac958c8ff086f63f0d8aea86b5a6 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -1286,20 +1286,6 @@ class JavaScriptBackend {
 
   MethodElement helperForMainArity() => commonElements.mainHasTooManyParameters;
 
-  /// Returns the filename for the output-unit named [name].
-  ///
-  /// The filename is of the form "<main output file>_<name>.part.js".
-  /// If [addExtension] is false, the ".part.js" suffix is left out.
-  String deferredPartFileName(String name, {bool addExtension: true}) {
-    assert(name != "");
-    String outPath = compiler.options.outputUri != null
-        ? compiler.options.outputUri.path
-        : "out";
-    String outName = outPath.substring(outPath.lastIndexOf('/') + 1);
-    String extension = addExtension ? ".part.js" : "";
-    return "${outName}_$name$extension";
-  }
-
   /// Enable deferred loading. Returns `true` if the backend supports deferred
   /// loading.
   bool enableDeferredLoadingIfSupported(Spannable node) => true;