Move ReturnInstr to new scheme (x64 and ia32) and implement more code in new ia32 compiler.

runtime/vm/flow_graph_compiler_x64.h

Index: runtime/vm/flow_graph_compiler_x64.h
===================================================================
--- runtime/vm/flow_graph_compiler_x64.h	(revision 8130)
+++ runtime/vm/flow_graph_compiler_x64.h	(working copy)
@@ -50,6 +50,18 @@
                       Register reg1,
                       Register reg2);
 
+  bool is_optimizing() const { return is_optimizing_; }
+  const ParsedFunction& parsed_function() const { return parsed_function_; }
+
+  void GenerateCallRuntime(intptr_t cid,
+                           intptr_t token_index,
+                           intptr_t try_index,
+                           const RuntimeEntry& entry);
+  void AddCurrentDescriptor(PcDescriptors::Kind kind,
+                            intptr_t cid,
+                            intptr_t token_index,
+                            intptr_t try_index);
+
  private:
   friend class DeoptimizationStub;
 
@@ -74,8 +86,6 @@
 
   BlockEntryInstr* current_block() const { return current_block_; }
 
-  bool is_optimizing() const { return is_optimizing_; }
-
   // Bail out of the flow graph compiler.  Does not return to the caller.
   void Bailout(const char* reason);
 
@@ -123,14 +133,6 @@
                     intptr_t try_index,
                     const ExternalLabel* label,
                     PcDescriptors::Kind kind);
-  void GenerateCallRuntime(intptr_t cid,
-                           intptr_t token_index,
-                           intptr_t try_index,
-                           const RuntimeEntry& entry);
-  void AddCurrentDescriptor(PcDescriptors::Kind kind,
-                            intptr_t cid,
-                            intptr_t token_index,
-                            intptr_t try_index);
 
   // Type checking helper methods.
   void CheckClasses(const GrowableArray<const Class*>& classes,