Reland of Avoid Context::Enter and Context::Exit if we're reentering the...

Reland of Avoid Context::Enter and Context::Exit if we're reentering the active and last entered context (patchset #1 id:1 of https://codereview.chromium.org/2140563002/ )

Reason for reland:
https://codereview.chromium.org/2122953002 fixed context issues.

Original issue's description:
> Revert of Avoid Context::Enter and Context::Exit if we're reentering the active and last entered context (patchset #2 id:20001 of https://codereview.chromium.org/2131483002/ )
>
> Reason for revert:
> crashes: crbug.com/626719
>
> Original issue's description:
> > Avoid Context::Enter and Context::Exit if we're reentering the active and last entered context
> >
> > A bit of browsing around indicates that the new fast-path is taken most of the time:
> >    3496 Entering new
> >  152295 Reentering same
> >
> > BUG=
> >
> > Committed: https://crrev.com/1829eb661ef1cf432fb551bcb193f521a219d490
> > Cr-Commit-Position: refs/heads/master@{#37570}
>
> TBR=jochen@chromium.org,verwaest@chromium.org
> # Not skipping CQ checks because original CL landed more than 1 days ago.
> BUG=
>
> Committed: https://crrev.com/bec49a4876fdf8a20600ecdfc8534d0ef45c9528
> Cr-Commit-Position: refs/heads/master@{#37632}

TBR=jochen@chromium.org,verwaest@chromium.org,jkummerow@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=

Review-Url: https://codereview.chromium.org/2152803003
Cr-Commit-Position: refs/heads/master@{#37778}

src/api.cc

@@ -183,7 +183,17 @@ class CallDepthScope {
     DCHECK(!isolate_->external_caught_exception());
     isolate_->IncrementJsCallsFromApiCounter();
     isolate_->handle_scope_implementer()->IncrementCallDepth();
-    if (!context_.IsEmpty()) context_->Enter();
+    if (!context.IsEmpty()) {
+      i::Handle<i::Context> env = Utils::OpenHandle(*context);
+      i::HandleScopeImplementer* impl = isolate->handle_scope_implementer();
+      if (isolate->context() != nullptr &&
+          isolate->context()->native_context() == env->native_context() &&
+          impl->LastEnteredContextWas(env)) {
+        context_ = Local<Context>();
+      } else {
+        context_->Enter();
+      }
+    }
     if (do_callback_) isolate_->FireBeforeCallEnteredCallback();
   }
   ~CallDepthScope() {