Add parseFontFaceDescriptor for @font-face handling

Source/core/css/StyleRule.cpp

Index: Source/core/css/StyleRule.cpp
diff --git a/Source/core/css/StyleRule.cpp b/Source/core/css/StyleRule.cpp
index dc810357ca37e3125b526763bc3498a1a480db4b..7eb6e6e85eef3b729d0f45619f9e0e078849e65f 100644
--- a/Source/core/css/StyleRule.cpp
+++ b/Source/core/css/StyleRule.cpp
@@ -29,6 +29,7 @@
 #include "core/css/CSSPageRule.h"
 #include "core/css/CSSStyleRule.h"
 #include "core/css/CSSSupportsRule.h"
+#include "core/css/CSSValueList.h"
 #include "core/css/CSSViewportRule.h"
 #include "core/css/StylePropertySet.h"
 #include "core/css/StyleRuleImport.h"
@@ -347,9 +348,18 @@ MutableStylePropertySet& StyleRuleFontFace::mutableProperties()
     return *toMutableStylePropertySet(m_properties);
 }
 
-void StyleRuleFontFace::setProperties(PassRefPtrWillBeRawPtr<StylePropertySet> properties)
+bool StyleRuleFontFace::setProperties(PassRefPtrWillBeRawPtr<StylePropertySet> properties)
 {
+    // FIXME: This logic should be in CSSPropertyParser
+    // FIXME: Shouldn't we fail if font-family or src aren't specified?
+    for (unsigned i = 0; i < properties->propertyCount(); ++i) {
+        StylePropertySet::PropertyReference property = properties->propertyAt(i);
+        if (property.id() == CSSPropertyFontFamily && (!property.value()->isValueList() || toCSSValueList(property.value())->length() != 1))
+            return false;
+    }
+
     m_properties = properties;
+    return true;
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(StyleRuleFontFace)