Fix assertion when parsing @namespace/@import with url(<bad-string-token>)

third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/parser/CSSParserImpl.h"
 
 #include "core/css/CSSCustomIdentValue.h"
 #include "core/css/CSSCustomPropertyDeclaration.h"
 #include "core/css/CSSKeyframesRule.h"
 #include "core/css/CSSStyleSheet.h"
@@ skipping 427 matching lines @@
     const CSSParserToken& token = range.peek();
 
     if (token.type() == StringToken || token.type() == UrlToken)
         return range.consumeIncludingWhitespace().value().toAtomicString();
 
     if (token.type() != FunctionToken || !equalIgnoringASCIICase(token.value(), "url"))
         return AtomicString();
 
     CSSParserTokenRange contents = range.consumeBlock();
     const CSSParserToken& uri = contents.consumeIncludingWhitespace();
-    ASSERT(uri.type() == StringToken);
-    if (!contents.atEnd())
+    if (uri.type() == BadStringToken || !contents.atEnd())
         return AtomicString();
+    DCHECK_EQ(uri.type(), StringToken);
     return uri.value().toAtomicString();
 }
 
 StyleRuleCharset* CSSParserImpl::consumeCharsetRule(CSSParserTokenRange prelude)
 {
     prelude.consumeWhitespace();
     const CSSParserToken& string = prelude.consumeIncludingWhitespace();
     if (string.type() != StringToken || !prelude.atEnd())
         return nullptr; // Parse error, expected a single string
     return StyleRuleCharset::create();
@@ skipping 362 matching lines @@
         else
             return nullptr; // Parser error, invalid value in keyframe selector
         if (range.atEnd())
             return result;
         if (range.consume().type() != CommaToken)
             return nullptr; // Parser error
     }
 }
 
 } // namespace blink