Add CoreClasses

pkg/compiler/lib/src/js_emitter/program_builder/collector.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart b/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
index 69babce0b9209603bc396822d64e2ba45d90f64e..d5a0794225371770ecb28d6cb9176da112bfe8a7 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
@@ -42,6 +42,8 @@ class Collector {
 
   JavaScriptBackend get backend => compiler.backend;
 
+  CoreClasses get coreClasses => compiler.coreClasses;
+
   Collector(this.compiler, this.namer, this.rtiNeededClasses, this.emitter);
 
   Set<ClassElement> computeInterceptorsReferencedFromConstants() {
@@ -67,7 +69,7 @@ class Collector {
     Set<ClassElement> unneededClasses = new Set<ClassElement>();
     // The [Bool] class is not marked as abstract, but has a factory
     // constructor that always throws. We never need to emit it.
-    unneededClasses.add(compiler.boolClass);
+    unneededClasses.add(coreClasses.boolClass);
 
     // Go over specialized interceptors and then constants to know which
     // interceptors are needed.
@@ -84,7 +86,7 @@ class Collector {
     // Add unneeded interceptors to the [unneededClasses] set.
     for (ClassElement interceptor in backend.interceptedClasses) {
       if (!needed.contains(interceptor)
-          && interceptor != compiler.objectClass) {
+          && interceptor != coreClasses.objectClass) {
         unneededClasses.add(interceptor);
       }
     }
@@ -214,22 +216,22 @@ class Collector {
 
     // TODO(18175, floitsch): remove once issue 18175 is fixed.
     if (neededClasses.contains(backend.jsIntClass)) {
-      neededClasses.add(compiler.intClass);
+      neededClasses.add(coreClasses.intClass);
     }
     if (neededClasses.contains(backend.jsDoubleClass)) {
-      neededClasses.add(compiler.doubleClass);
+      neededClasses.add(coreClasses.doubleClass);
     }
     if (neededClasses.contains(backend.jsNumberClass)) {
-      neededClasses.add(compiler.numClass);
+      neededClasses.add(coreClasses.numClass);
     }
     if (neededClasses.contains(backend.jsStringClass)) {
-      neededClasses.add(compiler.stringClass);
+      neededClasses.add(coreClasses.stringClass);
     }
     if (neededClasses.contains(backend.jsBoolClass)) {
-      neededClasses.add(compiler.boolClass);
+      neededClasses.add(coreClasses.boolClass);
     }
     if (neededClasses.contains(backend.jsArrayClass)) {
-      neededClasses.add(compiler.listClass);
+      neededClasses.add(coreClasses.listClass);
     }
 
     // 4. Finally, sort the classes.