Further reduce use of Element in codegen.

pkg/compiler/lib/src/ssa/builder.dart

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 296aa8114f45c90314e604602647c51b92af769e..686bb986e2755b0d8c39372de62f33364aa609b4 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -350,7 +350,7 @@ class SsaBuilder extends ast.Visitor
    * [selector]) in a specific order (see [addDynamicSendArgumentsToList]).
    */
   List<HInstruction> completeDynamicSendArgumentsList(Selector selector,
-      FunctionElement function, List<HInstruction> providedArguments) {
+      MethodElement function, List<HInstruction> providedArguments) {
     assert(selector.applies(function));
     FunctionSignature signature = function.functionSignature;
     List<HInstruction> compiledArguments = new List<HInstruction>(
@@ -423,7 +423,7 @@ class SsaBuilder extends ast.Visitor
 
     if (compiler.elementHasCompileTimeError(element)) return false;
 
-    FunctionElement function = element;
+    MethodElement function = element;
     ResolvedAst functionResolvedAst = function.resolvedAst;
     bool insideLoop = loopDepth > 0 || graph.calledInLoop;