SVG doesn't recognize rem units

Source/core/svg/SVGLengthTearOff.cpp

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 37 matching lines @@
 
 inline bool canResolveRelativeUnits(const SVGElement* contextElement)
 {
     return contextElement && contextElement->inDocument();
 }
 
 } // namespace
 
 SVGLengthType SVGLengthTearOff::unitType()
 {
-    return target()->unitType();
+    return hasExposedLengthUnit() ? target()->unitType() : LengthTypeUnknown;
 }
 
 SVGLengthMode SVGLengthTearOff::unitMode()
 {
     return target()->unitMode();
 }
 
 float SVGLengthTearOff::value(ExceptionState& exceptionState)
 {
     if (target()->isRelative() && !canResolveRelativeUnits(contextElement())) {
@@ skipping 32 matching lines @@
     if (isImmutable()) {
         es.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
     target()->setValueInSpecifiedUnits(value);
     commitChange();
 }
 
 String SVGLengthTearOff::valueAsString()
 {
-    return target()->valueAsString();
+    return hasExposedLengthUnit() ? target()->valueAsString() : String::number(0);

[Erik Dahlström (inactive), 2015/03/31 09:20:50]

Not all <length> properties have 0 (with no unit) as the default (lacuna) value,
e.g https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementCXAttribute.

See http://jsfiddle.net/ffwn1k4t/ and http://jsfiddle.net/ffwn1k4t/1/.

It looks like returning 0 here for "unknown" values is what blink used to do, so
it isn't a functional change really. However, I do think that gecko is more
correct in returning "50%" for cx.

[Shanmuga Pandi, 2015/04/01 15:01:37]

Added TODO note. I will work on this issue seperately.

[Erik Dahlström (inactive), 2015/04/02 07:58:40]

Acknowledged.

 }
 
 void SVGLengthTearOff::setValueAsString(const String& str, ExceptionState& es)
 {
     if (isImmutable()) {
         es.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
 
+    String oldValue = target()->valueAsString();
+
     target()->setValueAsString(str, es);
+
+    if (!es.hadException() && !hasExposedLengthUnit()) {
+        target()->setValueAsString(oldValue, ASSERT_NO_EXCEPTION); // rollback t o old value
+        es.throwDOMException(SyntaxError, "The value provided ('" + str + "') is invalid.");
+        return;
+    }
+
     commitChange();
 }
 
 void SVGLengthTearOff::newValueSpecifiedUnits(unsigned short unitType, float valueInSpecifiedUnits, ExceptionState& exceptionState)
 {
     if (isImmutable()) {
         exceptionState.throwDOMException(NoModificationAllowedError, "The object is read-only.");
         return;
     }
 
@@ skipping 28 matching lines @@
     target()->convertToSpecifiedUnits(toSVGLengthType(unitType), lengthContext);
     commitChange();
 }
 
 SVGLengthTearOff::SVGLengthTearOff(PassRefPtrWillBeRawPtr<SVGLength> target, SVGElement* contextElement, PropertyIsAnimValType propertyIsAnimVal, const QualifiedName& attributeName)
     : SVGPropertyTearOff<SVGLength>(target, contextElement, propertyIsAnimVal, attributeName)
 {
 }
 
 }