Use fallback in LayoutThemeMobile on mac.

third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp

Index: third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp b/third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp
index f93224325d3b13c225da8db1b89879a2bea0820b..b57673fea4ae3430649aea56436e681a70451cbb 100644
--- a/third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutThemeMobile.cpp
@@ -76,4 +76,15 @@ void LayoutThemeMobile::adjustInnerSpinButtonStyle(ComputedStyle& style) const
     }
 }
 
+bool LayoutThemeMobile::shouldUseFallbackTheme(const ComputedStyle& style) const
+{
+#if OS(MACOSX)
+    // Mac WebThemeEngine cannot handle these controls.
+    ControlPart part = style.appearance();
+    if (part == CheckboxPart || part == RadioPart)
+        return true;
+#endif
+    return LayoutThemeDefault::shouldUseFallbackTheme(style);
+}
+
 } // namespace blink