Start propagating non-primitive types in the backend, and fold instructions that know about the typ…

lib/compiler/implementation/ssa/codegen.dart

Index: lib/compiler/implementation/ssa/codegen.dart
===================================================================
--- lib/compiler/implementation/ssa/codegen.dart	(revision 6727)
+++ lib/compiler/implementation/ssa/codegen.dart	(working copy)
@@ -1006,7 +1006,13 @@
       buffer.add(compiler.namer.instanceMethodInvocationName(
           currentLibrary, node.name, node.selector));
       visitArguments(node.inputs);
-      compiler.registerDynamicInvocation(node.name, node.selector);
+      if (node.element !== null) {
+        // If we know we're calling a specific method, register that
+        // method only.
+        compiler.registerDynamicInvocationOf(node.element);
+      } else {
+        compiler.registerDynamicInvocation(node.name, node.selector);
+      }
     }
     endExpression(JSPrecedence.CALL_PRECEDENCE);
   }