Remove Collection, Collections and clean up List/Set/Queue implementations of retain/remove.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
index 7a21128eb52a95a8a45a303441b74ea327b3c400..8abad790c5e7a694f8d9f90c72f4e071f2a41a70 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
@@ -1729,7 +1729,7 @@ class CodeEmitterTask extends CompilerTask {
     // interceptors are needed.
     Set<ClassElement> needed = new Set<ClassElement>();
     backend.specializedGetInterceptors.forEach(
-        (_, Collection<ClassElement> elements) {
+        (_, Iterable<ClassElement> elements) {
           needed.addAll(elements);
         }
     );
@@ -2420,7 +2420,7 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
 
   void emitGetInterceptorMethod(CodeBuffer buffer,
                                 String key,
-                                Collection<ClassElement> classes) {
+                                Iterable<ClassElement> classes) {
     jsAst.Statement buildReturnInterceptor(ClassElement cls) {
       return js.return_(js(namer.isolateAccess(cls))['prototype']);
     }
@@ -2590,7 +2590,7 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
   void emitGetInterceptorMethods(CodeBuffer buffer) {
     var specializedGetInterceptors = backend.specializedGetInterceptors;
     for (String name in specializedGetInterceptors.keys.toList()..sort()) {
-      Collection<ClassElement> classes = specializedGetInterceptors[name];
+      Iterable<ClassElement> classes = specializedGetInterceptors[name];
       emitGetInterceptorMethod(buffer, name, classes);
     }
   }