Make {StackFrame::unchecked_code} fail gracefully.

This makes sure that all overrides of {StackFrame::unchecked_code}
return a value, even if there is no {Code} object associated with the
frame. This ensures debug functions like {StackTraceFailureMessage}
continue working for all stack traces.

R=neis@chromium.org
BUG=chromium:952761

Change-Id: Ie42b301e4d43ebf67acc80e6c1b7bcb4cdc7c947
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1566515Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60844}

src/frames.cc

@@ -620,7 +620,7 @@ Code ConstructEntryFrame::unchecked_code() const {
   return isolate()->heap()->builtin(Builtins::kJSConstructEntry);
 }
 
-Code ExitFrame::unchecked_code() const { UNREACHABLE(); }
+Code ExitFrame::unchecked_code() const { return Code(); }
 
 void ExitFrame::ComputeCallerState(State* state) const {
   // Set up the caller state.
@@ -1793,7 +1793,7 @@ Address InternalFrame::GetCallerStackPointer() const {
   return fp() + StandardFrameConstants::kCallerSPOffset;
 }
 
-Code InternalFrame::unchecked_code() const { UNREACHABLE(); }
+Code InternalFrame::unchecked_code() const { return Code(); }
 
 void WasmCompiledFrame::Print(StringStream* accumulator, PrintMode mode,
                               int index) const {
@@ -1928,7 +1928,7 @@ void WasmInterpreterEntryFrame::Summarize(
   }
 }
 
-Code WasmInterpreterEntryFrame::unchecked_code() const { UNREACHABLE(); }
+Code WasmInterpreterEntryFrame::unchecked_code() const { return Code(); }
 
 WasmInstanceObject WasmInterpreterEntryFrame::wasm_instance() const {
   const int offset = WasmCompiledFrameConstants::kWasmInstanceOffset;

src/isolate.cc

@@ -530,7 +530,6 @@ StackTraceFailureMessage::StackTraceFailureMessage(Isolate* isolate, void* ptr1,
   size_t i = 0;
   StackFrameIterator it(isolate);
   for (; !it.done() && i < code_objects_length; it.Advance()) {
-    if (it.frame()->type() == StackFrame::INTERNAL) continue;
     code_objects_[i++] =
         reinterpret_cast<void*>(it.frame()->unchecked_code().ptr());
   }