[PE] Workaround crash on chunk effect escaping layer effect

Workaround for now. We should investigate the root cause when we have
concrete test cases. We had the workaround before
https://chromium-review.googlesource.com/976947.

Bug: 829269
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I4bd729c4c443a6d39f6628852884466b5f23922f
Reviewed-on: https://chromium-review.googlesource.com/998054Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548624}

third_party/WebKit/Source/platform/graphics/compositing/PaintChunksToCcLayer.cpp

@@ -345,6 +345,8 @@ void ConversionContext::SwitchToEffect(
   const EffectPaintPropertyNode* lca_effect =
       &LowestCommonAncestor(*target_effect, *current_effect_);
   while (current_effect_ != lca_effect) {
+    // This EndClips() and the later EndEffect() pop to the parent effect.
+    EndClips();
 #if DCHECK_IS_ON()
     DCHECK(state_stack_.size())
         << "Error: Chunk has an effect that escapes layer's effect.\n"
@@ -354,8 +356,6 @@ void ConversionContext::SwitchToEffect(
 #endif
     if (!state_stack_.size())
       break;
-    // Pop to the parent effect.
-    EndClips();
     EndEffect();
   }