Refactor lithium codegen to not pass around block_ids

src/x64/lithium-codegen-x64.h

Index: src/x64/lithium-codegen-x64.h
diff --git a/src/x64/lithium-codegen-x64.h b/src/x64/lithium-codegen-x64.h
index 31dd9c44cccc681c385858610a9efcf9bb44ebda..0b30c2e469ec2793bdd6c138c23da1b73b556718 100644
--- a/src/x64/lithium-codegen-x64.h
+++ b/src/x64/lithium-codegen-x64.h
@@ -79,7 +79,6 @@ class LCodeGen BASE_EMBEDDED {
   Heap* heap() const { return isolate()->heap(); }
   Zone* zone() const { return zone_; }
 
-  // TODO(svenpanne) Use this consistently.
   int LookupDestination(int block_id) const {
     return chunk()->LookupDestination(block_id);
   }
@@ -282,7 +281,8 @@ class LCodeGen BASE_EMBEDDED {
 
   static Condition TokenToCondition(Token::Value op, bool is_unsigned);
   void EmitGoto(int block);
-  void EmitBranch(int left_block, int right_block, Condition cc);
+  template<class InstrType>
+  void EmitBranch(InstrType instr, Condition cc);
   void EmitNumberUntagD(
       Register input,
       XMMRegister result,