X87: Reland of [debugger] do not restart frames that reference new.target for...

X87: Reland of [debugger] do not restart frames that reference new.target for liveedit. (patchset #1 id:1 of https://codereview.chromium.org/1493863004/ )

  port 15cb3fde (r32587)

  original commit message:
  Reason for revert:
  Didn't help...

  Original issue's description:
  > Revert of [debugger] do not restart frames that reference new.target for liveedit. (patchset #1 id:1 of https://codereview.chromium.org/1493363002/ )
  >
  > Reason for revert:
  > [Sheriff] Speculative revert for https://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/3225
  >
  > Original issue's description:
  > > [debugger] do not restart frames that reference new.target for liveedit.
  > >
  > > R=mstarzinger@chromium.org
  > >
  > > Committed: https://crrev.com/6fca870240bdbb07a365189b5eb0c98fa65b3682
  > > Cr-Commit-Position: refs/heads/master@{#32572}
  >
  > TBR=mstarzinger@chromium.org,yangguo@chromium.org
  > NOPRESUBMIT=true
  > NOTREECHECKS=true
  > NOTRY=true
  >
  > Committed: https://crrev.com/1a61dab34b9849f3f70a42ce69317e22758c53a1
  > Cr-Commit-Position: refs/heads/master@{#32582}

BUG=

Review URL: https://codereview.chromium.org/1501323002

Cr-Commit-Position: refs/heads/master@{#32637}

src/debug/x87/debug-x87.cc

@@ -125,13 +125,16 @@ void DebugCodegen::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
   // Load context from the function.
   __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
 
+  // Clear new.target register as a safety measure.
+  __ mov(edx, masm->isolate()->factory()->undefined_value());
+
   // Get function code.
-  __ mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
-  __ mov(edx, FieldOperand(edx, SharedFunctionInfo::kCodeOffset));
-  __ lea(edx, FieldOperand(edx, Code::kHeaderSize));
+  __ mov(ebx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
+  __ mov(ebx, FieldOperand(ebx, SharedFunctionInfo::kCodeOffset));
+  __ lea(ebx, FieldOperand(ebx, Code::kHeaderSize));
 
   // Re-run JSFunction, edi is function, esi is context.
-  __ jmp(edx);
+  __ jmp(ebx);
 }