[wasm] fix crash using devtools pause button in wasm

Check for is_javascript in Debug::AllFramesOnStackAreBlackboxed,
instead of assuming all frames are javascript frames.

Fix is thanks to dgozman: https://crbug.com/896093#c3

Bug: chromium:896093
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I6b735d904c3fd036d4589d65f10673b81b8f326c
Reviewed-on: https://chromium-review.googlesource.com/c/1295552Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56970}

src/debug/debug.cc

@@ -1822,6 +1822,7 @@ bool Debug::IsBlackboxed(Handle<SharedFunctionInfo> shared) {
 bool Debug::AllFramesOnStackAreBlackboxed() {
   HandleScope scope(isolate_);
   for (StackTraceFrameIterator it(isolate_); !it.done(); it.Advance()) {
+    if (!it.is_javascript()) continue;
     if (!IsFrameBlackboxed(it.javascript_frame())) return false;
   }
   return true;