[DevTools] ignore inspector interruptions during CreateContext

Otherwise crash can occur.

R=pfeldman@chromium.org

Bug: chromium:757778
Change-Id: Idbe43f15bf620af41738e6e27c7a5ddf5bbf3067
Reviewed-on: https://chromium-review.googlesource.com/685270
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505879}

third_party/WebKit/Source/bindings/core/v8/LocalWindowProxy.cpp

@@ -127,7 +127,12 @@ void LocalWindowProxy::Initialize() {
                                                          : non_main_frame_hist);
 
   ScriptForbiddenScope::AllowUserAgentScript allow_script;
-
+  // Inspector may request V8 interruption to process DevTools protocol
+  // commands, processing can force JavaScript execution. Since JavaScript
+  // evaluation is forbiden during creating of snapshot, we should ignore any
+  // inspector interruption to avoid JavaScript execution.
+  InspectorTaskRunner::IgnoreInterruptsScope inspector_ignore_interrupts(
+      MainThreadDebugger::Instance()->TaskRunner());
   v8::HandleScope handle_scope(GetIsolate());
 
   CreateContext();