[runtime] Unify and simplify how frames are marked

src/debug/x64/debug-x64.cc

Index: src/debug/x64/debug-x64.cc
diff --git a/src/debug/x64/debug-x64.cc b/src/debug/x64/debug-x64.cc
index f7fbe7691e4bcfcc1c375e8a7e5bc1bcb2fc137b..094e7b608ece3dc54ac5f1f708a057b62854a9cf 100644
--- a/src/debug/x64/debug-x64.cc
+++ b/src/debug/x64/debug-x64.cc
@@ -111,9 +111,12 @@ void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
 
 void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
   // We do not know our frame height, but set rsp based on rbp.
-  __ leap(rsp, Operand(rbp, -1 * kPointerSize));
-
+  __ leap(rsp, Operand(rbp, FrameDropperFrameConstants::kFunctionOffset));
   __ Pop(rdi);  // Function.
+  __ addp(rsp,
+          Immediate(-FrameDropperFrameConstants::kCodeOffset));  // INTERNAL
+                                                                 // frame marker
+                                                                 // and code
   __ popq(rbp);
 
   ParameterCount dummy(0);