Move remaining helpers to BackendHelpers

pkg/compiler/lib/src/cps_ir/type_propagation.dart

Index: pkg/compiler/lib/src/cps_ir/type_propagation.dart
diff --git a/pkg/compiler/lib/src/cps_ir/type_propagation.dart b/pkg/compiler/lib/src/cps_ir/type_propagation.dart
index b583dc49a4e828f7755580d2ce047abb7888cf18..eb7f202075131dadcfeb0595e8935316d53a77e9 100644
--- a/pkg/compiler/lib/src/cps_ir/type_propagation.dart
+++ b/pkg/compiler/lib/src/cps_ir/type_propagation.dart
@@ -19,6 +19,8 @@ import '../dart_types.dart' as types;
 import '../elements/elements.dart';
 import '../io/source_information.dart' show
     SourceInformation;
+import '../js_backend/backend_helpers.dart' show
+    BackendHelpers;
 import '../js_backend/js_backend.dart' show
     JavaScriptBackend;
 import '../js_backend/codegen/task.dart' show
@@ -664,6 +666,7 @@ class TransformingVisitor extends DeepRecursiveVisitor {
   final CpsFunctionCompiler functionCompiler;
 
   JavaScriptBackend get backend => compiler.backend;
+  BackendHelpers get helpers => backend.helpers;
   TypeMaskSystem get typeSystem => lattice.typeSystem;
   types.DartTypes get dartTypes => lattice.dartTypes;
   Map<Variable, ConstantValue> get values => analyzer.values;
@@ -1005,8 +1008,8 @@ class TransformingVisitor extends DeepRecursiveVisitor {
         for (Element target in getAllTargets(left.type, node.selector)) {
           ClassElement clazz = target.enclosingClass.declaration;
           if (clazz != compiler.world.objectClass &&
-              clazz != backend.jsInterceptorClass &&
-              clazz != backend.jsNullClass) {
+              clazz != helpers.jsInterceptorClass &&
+              clazz != helpers.jsNullClass) {
             behavesLikeIdentical = false;
             break;
           }
@@ -1185,7 +1188,7 @@ class TransformingVisitor extends DeepRecursiveVisitor {
         <Primitive>[index, cps.letPrim(new GetLength(list))]);
     cps.ifTruthy(isTooLarge).invokeContinuation(fail);
     cps.insideContinuation(fail).invokeStaticThrower(
-        backend.helpers.throwIndexOutOfBoundsError,
+        helpers.throwIndexOutOfBoundsError,
         <Primitive>[list, index]);
     return cps;
   }
@@ -1203,7 +1206,7 @@ class TransformingVisitor extends DeepRecursiveVisitor {
         BuiltinOperator.StrictNeq,
         <Primitive>[originalLength, cps.letPrim(new GetLength(list))]);
     cps.ifTruthy(lengthChanged).invokeStaticThrower(
-        backend.helpers.throwConcurrentModificationError,
+        helpers.throwConcurrentModificationError,
         <Primitive>[list]);
     return cps;
   }
@@ -1310,7 +1313,7 @@ class TransformingVisitor extends DeepRecursiveVisitor {
             [length, cps.makeZero()]);
         CpsFragment fail = cps.ifTruthy(isEmpty);
         fail.invokeStaticThrower(
-            backend.helpers.throwIndexOutOfBoundsError,
+            helpers.throwIndexOutOfBoundsError,
             [list, fail.makeConstant(new IntConstantValue(-1))]);
         Primitive removedItem = cps.invokeBuiltin(BuiltinMethod.Pop,
             list,
@@ -2203,19 +2206,19 @@ class TransformingVisitor extends DeepRecursiveVisitor {
     if (lattice.isDefinitelyInt(value)) {
       // Classes like JSUInt31 and JSUInt32 do not exist at runtime, so ensure
       // all the int classes get mapped tor their runtime class.
-      singleClass = backend.jsIntClass;
+      singleClass = helpers.jsIntClass;
     } else if (lattice.isDefinitelyNum(value)) {
       if (jsNumberClassSuffices(node)) {
-        singleClass = backend.jsNumberClass;
+        singleClass = helpers.jsNumberClass;
       }
     } else if (lattice.isDefinitelyNativeList(value)) {
       // Ensure all the array subclasses get mapped to the array class.
-      singleClass = backend.jsArrayClass;
+      singleClass = helpers.jsArrayClass;
     } else {
       singleClass = typeSystem.singleClass(value.type);
     }
     if (singleClass != null &&
-        singleClass.isSubclassOf(backend.jsInterceptorClass)) {
+        singleClass.isSubclassOf(helpers.jsInterceptorClass)) {
       node.constantValue = new InterceptorConstantValue(singleClass.rawType);
     }
     // Filter out intercepted classes that do not match the input type.
@@ -2245,8 +2248,8 @@ class TransformingVisitor extends DeepRecursiveVisitor {
         if (invoke.receiver != ref) return false;
         var interceptedClasses =
             functionCompiler.glue.getInterceptedClassesOn(invoke.selector);
-        if (interceptedClasses.contains(backend.jsDoubleClass)) return false;
-        if (interceptedClasses.contains(backend.jsIntClass)) return false;
+        if (interceptedClasses.contains(helpers.jsDoubleClass)) return false;
+        if (interceptedClasses.contains(helpers.jsIntClass)) return false;
         continue;
       }
       // Other uses need full distinction.
@@ -2908,7 +2911,7 @@ class TypePropagationVisitor implements Visitor {
     if (value.isNothing) {
       setValue(node, nothing);
     } else if (value.isNullable &&
-        !node.interceptedClasses.contains(backend.jsNullClass)) {
+        !node.interceptedClasses.contains(backend.helpers.jsNullClass)) {
       // If the input is null and null is not mapped to an interceptor then
       // null gets returned.
       // TODO(asgerf): Add the NullInterceptor when it enables us to