Cleanup the way the debugger stores live registers when entering at a break...

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
===================================================================
--- src/x64/code-stubs-x64.cc	(revision 5352)
+++ src/x64/code-stubs-x64.cc	(working copy)
@@ -2476,7 +2476,7 @@
   Label empty_result;
   Label prologue;
   Label promote_scheduled_exception;
-  __ EnterApiExitFrame(ExitFrame::MODE_NORMAL, kStackSpace, 0);
+  __ EnterApiExitFrame(kStackSpace, 0);
   ASSERT_EQ(kArgc, 4);
 #ifdef _WIN64
   // All the parameters should be set up by a caller.
@@ -2507,7 +2507,7 @@
   // It was non-zero.  Dereference to get the result value.
   __ movq(rax, Operand(rax, 0));
   __ bind(&prologue);
-  __ LeaveExitFrame(ExitFrame::MODE_NORMAL);
+  __ LeaveExitFrame();
   __ ret(0);
   __ bind(&promote_scheduled_exception);
   __ TailCallRuntime(Runtime::kPromoteScheduledException, 0, 1);
@@ -2617,7 +2617,7 @@
   __ j(zero, &failure_returned);
 
   // Exit the JavaScript to C++ exit frame.
-  __ LeaveExitFrame(mode_, result_size_);
+  __ LeaveExitFrame(result_size_);
   __ ret(0);
 
   // Handling of failure.
@@ -2721,7 +2721,7 @@
   // builtin once.
 
   // Enter the exit frame that transitions from JavaScript to C++.
-  __ EnterExitFrame(mode_, result_size_);
+  __ EnterExitFrame(result_size_);
 
   // rax: Holds the context at this point, but should not be used.
   //      On entry to code generated by GenerateCore, it must hold