Element model cleanup + prepare for easier reimplementation.

pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart

Index: pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
diff --git a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
index 00ad240b17e23ba58a2e7bc25cf92d3e6526bcad..1eae6e65ea2afabb9fa492386d38dbf4d3e803fd 100644
--- a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
+++ b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
@@ -1529,7 +1529,7 @@ class SimpleTypeInferrerVisitor<T>
         element = constructor.effectiveTarget.implementation;
       }
     }
-    if (element.isForeign(compiler.backend)) {
+    if (compiler.backend.isForeign(element)) {
       return handleForeignSend(node, element);
     }
     Selector selector = elements.getSelector(node);
@@ -1590,7 +1590,7 @@ class SimpleTypeInferrerVisitor<T>
 
   /// Handle invocation of a top level or static [function].
   T handleStaticFunctionInvoke(ast.Send node, MethodElement function) {
-    if (function.isForeign(compiler.backend)) {
+    if (compiler.backend.isForeign(function)) {
       return handleForeignSend(node, function);
     }
     ArgumentsTypes arguments = analyzeArguments(node.arguments);