[turbofan] Make VisitBranch and friends to backend specific.

This is required to fix a tricky branch fusion bug on ARM, which was
caused by the interaction between the architecture-independent and
architecture-specific parts of the InstructionSelector. In the end it
wasn't worth sharing a few common lines of code for the additional
complexity, especially if we also want to properly support architectures
without any dedicated flags register (i.e. MIPS).

TEST=mjsunit,unittests
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/651783003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24546 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/instruction-selector.h

@@ -169,22 +169,12 @@ class InstructionSelector FINAL {
   MACHINE_OP_LIST(DECLARE_GENERATOR)
 #undef DECLARE_GENERATOR
 
-  void VisitInt32AddWithOverflow(Node* node, FlagsContinuation* cont);
-  void VisitInt32SubWithOverflow(Node* node, FlagsContinuation* cont);
-
-  void VisitWord32Test(Node* node, FlagsContinuation* cont);
-  void VisitWord64Test(Node* node, FlagsContinuation* cont);
-  void VisitWord32Compare(Node* node, FlagsContinuation* cont);
-  void VisitWord64Compare(Node* node, FlagsContinuation* cont);
-  void VisitFloat64Compare(Node* node, FlagsContinuation* cont);
-
   void VisitFinish(Node* node);
   void VisitParameter(Node* node);
   void VisitPhi(Node* node);
   void VisitProjection(Node* node);
   void VisitConstant(Node* node);
-  void VisitCall(Node* call, BasicBlock* continuation,
-                 BasicBlock* deoptimization);
+  void VisitCall(Node* call);
   void VisitGoto(BasicBlock* target);
   void VisitBranch(Node* input, BasicBlock* tbranch, BasicBlock* fbranch);
   void VisitReturn(Node* value);