Fix pattern attribute handling for invalid regular expressions.

third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp

Index: third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp
diff --git a/third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp b/third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp
index a2856b8c9fe789268630f1698f74322f699fabed..a665fb96b97c19d62b58ed9fc65a9e7945d2d1d3 100644
--- a/third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp
+++ b/third_party/WebKit/Source/core/html/forms/BaseTextInputType.cpp
@@ -101,6 +101,8 @@ bool BaseTextInputType::patternMismatch(const String& value) const
         String pattern = "^(?:" + rawPattern + ")$";
         m_regexp.reset(new ScriptRegexp(pattern, TextCaseSensitive, MultilineDisabled, ScriptRegexp::UTF16));
         m_patternForRegexp = rawPattern;
+    } else if (!m_regexp->isValid()) {
+        return false;
     }
 
     int matchLength = 0;