Add test for paint underinvalidation fix with animated transform overflow.

third_party/WebKit/Source/web/tests/sim/SimTest.cpp

Index: third_party/WebKit/Source/web/tests/sim/SimTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/sim/SimTest.cpp b/third_party/WebKit/Source/web/tests/sim/SimTest.cpp
index 0ec638384be008294dcff6140b0506780043cf6d..e460e89abac2d148adb221cc96075f33dc6d1cf2 100644
--- a/third_party/WebKit/Source/web/tests/sim/SimTest.cpp
+++ b/third_party/WebKit/Source/web/tests/sim/SimTest.cpp
@@ -15,7 +15,10 @@
 
 namespace blink {
 
-SimTest::SimTest() : m_webViewClient(m_compositor) {
+SimTest::SimTest() : SimTest(nullptr) {
+}
+
+SimTest::SimTest(void (*updateSettingsFunc)(WebSettings*)) : m_webViewClient(m_compositor) {
   Document::setThreadedParsingEnabledForTesting(false);
   // Use the mock theme to get more predictable code paths, this also avoids
   // the OS callbacks in ScrollAnimatorMac which can schedule frames
@@ -25,7 +28,7 @@ SimTest::SimTest() : m_webViewClient(m_compositor) {
   // in the middle of a test.
   LayoutTestSupport::setMockThemeEnabledForTest(true);
   ScrollbarTheme::setMockScrollbarsEnabled(true);
-  m_webViewHelper.initialize(true, nullptr, &m_webViewClient);
+  m_webViewHelper.initialize(true, nullptr, &m_webViewClient, nullptr, updateSettingsFunc);
   m_compositor.setWebViewImpl(webView());
   m_page.setPage(webView().page());
 }