Start work on a non-complete type inferrer. Currently only analyzes return types.

sdk/lib/_internal/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 1599 matching lines @@
       // TODO(kasperl): If we have a typed selector for the call, we
       // may know something about the types of closures that need
       // the specific closure call method.
       Selector call = new Selector.callClosureFrom(selector);
       world.registerDynamicInvocation(call.name, call);
     }
 
     if (target != null) {
       // If we know we're calling a specific method, register that
       // method only.
+      assert(selector.typeKind != TypedSelectorKind.UNKNOWN);
       world.registerDynamicInvocationOf(target, selector);
     } else {
       SourceString name = node.selector.name;
       world.registerDynamicInvocation(name, selector);
     }
     registerInvoke(node);
   }
 
   void registerSetter(HInvokeDynamic node) {
     Selector selector = getOptimizedSelectorFor(node, node.selector);
@@ skipping 1358 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }