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

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

Index: sdk/lib/_internal/compiler/implementation/ssa/builder.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/builder.dart	(revision 18311)
+++ sdk/lib/_internal/compiler/implementation/ssa/builder.dart	(working copy)
@@ -3367,9 +3367,13 @@
       HInvokeStatic instruction = new HInvokeStatic(inputs, HType.UNKNOWN);
       // TODO(ngeoffray): Only do this if knowing the return type is

[kasperl, 2013/02/12 10:33:44]

Move TODO to recompilation branch.

[ngeoffray, 2013/02/12 11:58:22]

Done.

       // useful.
-      HType returnType =
-          builder.backend.optimisticReturnTypesWithRecompilationOnTypeChange(
-              currentElement, element);
+      HType returnType = mapInferredType(

[kasperl, 2013/02/12 10:33:44]

Maybe add a helper for getting the guaranteed HType for an element? Useful in at
least two places.

[ngeoffray, 2013/02/12 11:58:22]

Done.

+          compiler.typesTask.getGuaranteedTypeOfElement(element));
+      if (returnType.isUnknown()) {
+        returnType =
+            builder.backend.optimisticReturnTypesWithRecompilationOnTypeChange(
+                currentElement, element);
+      }
       if (returnType != null) instruction.guaranteedType = returnType;
       pushWithPosition(instruction, node);
     } else {
@@ -3561,7 +3565,14 @@
     }
     inputs.add(receiver);
     inputs.addAll(arguments);
-    return new HInvokeDynamicMethod(selector, inputs, isIntercepted);
+    HInstruction invoke = new HInvokeDynamicMethod(
+        selector, inputs, isIntercepted);
+    HType returnType = mapInferredType(
+        compiler.typesTask.getGuaranteedTypeOfNode(work.element, node));
+    if (returnType != null) {
+      invoke.guaranteedType = returnType;
+    }
+    return invoke;
   }
 
   visitSendSet(SendSet node) {