Tighten error checking from SVGLength parsing

Source/core/svg/SVGSVGElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 252 matching lines @@
 {
     if (isOutermostSVGSVGElement() && (name == SVGNames::widthAttr || name == SVGNames::heightAttr))
         return true;
     return SVGGraphicsElement::isPresentationAttribute(name);
 }
 
 void SVGSVGElement::collectStyleForPresentationAttribute(const QualifiedName& name, const AtomicString& value, MutableStylePropertySet* style)
 {
     if (isOutermostSVGSVGElement() && (name == SVGNames::widthAttr || name == SVGNames::heightAttr)) {
         RefPtr<SVGLength> length = SVGLength::create(LengthModeOther);
-        length->setValueAsString(value, IGNORE_EXCEPTION);
-        if (length->unitType() != LengthTypeUnknown) {
+        TrackExceptionState exceptionState;
+        length->setValueAsString(value, exceptionState);
+        if (!exceptionState.hadException()) {
             if (name == SVGNames::widthAttr)
                 addPropertyToPresentationAttributeStyle(style, CSSPropertyWidth, value);
             else if (name == SVGNames::heightAttr)
                 addPropertyToPresentationAttributeStyle(style, CSSPropertyHeight, value);
         }
     } else {
         SVGGraphicsElement::collectStyleForPresentationAttribute(name, value, style);
     }
 }
 
@@ skipping 479 matching lines @@
         view->preserveAspectRatio()->baseValue()->setMeetOrSlice(preserveAspectRatio()->currentValue()->meetOrSlice());
     }
 
     if (viewElement->hasAttribute(SVGNames::zoomAndPanAttr))
         view->setZoomAndPan(viewElement->zoomAndPan());
     else
         view->setZoomAndPan(zoomAndPan());
 }
 
 }