Disable under-invalidation checking in two video paint invalidation tests

third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html

Index: third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html
diff --git a/third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html b/third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html
index 8370a0ed36e27d00150d714cbc3d5734839fdf1e..8ca0c19e6a5856fccae1c3f98171df6e1a5d639c 100644
--- a/third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html
+++ b/third_party/WebKit/LayoutTests/paint/invalidation/video-unmute-repaint.html
@@ -11,6 +11,11 @@
 <p>This tests that we repaint the mute button when we change the volume</p>
 
 <script>
+    // Disable under-invalidation checking because we allow short period of
+    // under-invalidation of buffered ranges.
+    if (window.internals)
+        internals.runtimeFlags.paintUnderInvalidationCheckingEnabled = false;
+
     window.testIsAsync = true;
 
     var video = document.getElementById("v");