remove dependency on compiler from resolution

pkg/compiler/lib/src/typechecker.dart

Index: pkg/compiler/lib/src/typechecker.dart
diff --git a/pkg/compiler/lib/src/typechecker.dart b/pkg/compiler/lib/src/typechecker.dart
index 69137ab1fe80fdf67cc45060b05385a93e3a9f9c..008878d3f2b2629ecd93d445f12e02a14ac34c64 100644
--- a/pkg/compiler/lib/src/typechecker.dart
+++ b/pkg/compiler/lib/src/typechecker.dart
@@ -1742,11 +1742,7 @@ class TypeCheckerVisitor extends Visitor<DartType> {
 
   DartType visitAwait(Await node) {
     DartType expressionType = analyze(node.expression);
-    if (compiler.backend.supportsAsyncAwait) {
-      return types.flatten(expressionType);
-    } else {
-      return const DynamicType();
-    }
+    return types.flatten(expressionType);
   }
 
   DartType visitYield(Yield node) {
@@ -1869,31 +1865,29 @@ class TypeCheckerVisitor extends Visitor<DartType> {
   visitAsyncForIn(AsyncForIn node) {
     DartType elementType = computeForInElementType(node);
     DartType expressionType = analyze(node.expression);
-    if (compiler.backend.supportsAsyncAwait) {
-      DartType streamOfDynamic = coreTypes.streamType();
-      if (!types.isAssignable(expressionType, streamOfDynamic)) {
-        reportMessage(node.expression, MessageKind.NOT_ASSIGNABLE,
-            {'fromType': expressionType, 'toType': streamOfDynamic},
-            isHint: true);
-      } else {
-        InterfaceType interfaceType =
-            Types.computeInterfaceType(resolution, expressionType);
-        if (interfaceType != null) {
-          InterfaceType streamType =
-              interfaceType.asInstanceOf(streamOfDynamic.element);
-          if (streamType != null) {
-            DartType streamElementType = streamType.typeArguments.first;
-            if (!types.isAssignable(streamElementType, elementType)) {
-              reportMessage(
-                  node.expression,
-                  MessageKind.FORIN_NOT_ASSIGNABLE,
-                  {
-                    'currentType': streamElementType,
-                    'expressionType': expressionType,
-                    'elementType': elementType
-                  },
-                  isHint: true);
-            }
+    DartType streamOfDynamic = coreTypes.streamType();
+    if (!types.isAssignable(expressionType, streamOfDynamic)) {
+      reportMessage(node.expression, MessageKind.NOT_ASSIGNABLE,
+          {'fromType': expressionType, 'toType': streamOfDynamic},
+          isHint: true);
+    } else {
+      InterfaceType interfaceType =
+          Types.computeInterfaceType(resolution, expressionType);
+      if (interfaceType != null) {
+        InterfaceType streamType =
+            interfaceType.asInstanceOf(streamOfDynamic.element);
+        if (streamType != null) {
+          DartType streamElementType = streamType.typeArguments.first;
+          if (!types.isAssignable(streamElementType, elementType)) {
+            reportMessage(
+                node.expression,
+                MessageKind.FORIN_NOT_ASSIGNABLE,
+                {
+                  'currentType': streamElementType,
+                  'expressionType': expressionType,
+                  'elementType': elementType
+                },
+                isHint: true);
           }
         }
       }