ASSERT_NOT_REACHED() in EventRegionContext::popClip()

https://bugs.webkit.org/show_bug.cgi?id=213905

Reviewed by Daniel Bates.

Fix an assertion seen on bing.com, tesla.com etc where event region painting
would have mismatched push/pop because of an obvious code error.

I spent too long trying to make a testcase and gave up.

* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::restoreClip):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@263980 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Author: [email protected]

Source/WebCore/ChangeLog

@@ -1,3 +1,18 @@
+2020-07-06  Simon Fraser  <[email protected]>
+
+        ASSERT_NOT_REACHED() in EventRegionContext::popClip()
+        https://bugs.webkit.org/show_bug.cgi?id=213905
+
+        Reviewed by Daniel Bates.
+
+        Fix an assertion seen on bing.com, tesla.com etc where event region painting
+        would have mismatched push/pop because of an obvious code error.
+
+        I spent too long trying to make a testcase and gave up.
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::restoreClip):
+
 2020-07-06  Sam Weinig  <[email protected]>
 
         Compile-time enable (but leave disabled at runtime by default) date/time input types on macOS to allow testing of cross platform (e.g. DOM) aspects of the controls

Source/WebCore/rendering/RenderLayer.cpp

@@ -4213,12 +4213,12 @@ void RenderLayer::clipToRect(GraphicsContext& context, const LayerPaintingInfo&
 
 void RenderLayer::restoreClip(GraphicsContext& context, const LayerPaintingInfo& paintingInfo, const ClipRect& clipRect)
 {
-    if ((!clipRect.isInfinite() && clipRect.rect() != paintingInfo.paintDirtyRect) || clipRect.affectedByRadius()) {
+    bool needsClipping = !clipRect.isInfinite() && clipRect.rect() != paintingInfo.paintDirtyRect;
+    if (needsClipping || clipRect.affectedByRadius())
         context.restore();
 
-        if (paintingInfo.eventRegionContext)
-            paintingInfo.eventRegionContext->popClip();
-    }
+    if (needsClipping && paintingInfo.eventRegionContext)
+        paintingInfo.eventRegionContext->popClip();
 }
 
 static void performOverlapTests(OverlapTestRequestMap& overlapTestRequests, const RenderLayer* rootLayer, const RenderLayer* layer)