Fixed a variable that may be used uninitialized.

Source/core/css/parser/BisonCSSParser-in.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 313 matching lines @@
     // will set "ok" to "false" if the entire passed-in character range does
     // not represent a double.
     bool ok;
     number = charactersToDouble(characters, length, &ok);
     return ok;
 }
 
 static bool parseSimpleLengthValue(MutableStylePropertySet* declaration, CSSPropertyID propertyId, const String& string, bool important, CSSParserMode cssParserMode)
 {
     ASSERT(!string.isEmpty());
-    bool acceptsNegativeNumbers;
+    bool acceptsNegativeNumbers = false;
 
     // In @viewport, width and height are shorthands, not simple length values.
     if (isCSSViewportParsingEnabledForMode(cssParserMode) || !isSimpleLengthPropertyID(propertyId, acceptsNegativeNumbers))
         return false;
 
     unsigned length = string.length();
     double number;
     CSSPrimitiveValue::UnitTypes unit = CSSPrimitiveValue::CSS_NUMBER;
 
     if (string.is8Bit()) {
@@ skipping 1827 matching lines @@
     rule->setProperties(createStylePropertySet());
     clearProperties();
 
     StyleRuleViewport* result = rule.get();
     m_parsedRules.append(rule.release());
 
     return result;
 }
 
 }