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();
+    // TODO(shanmuga.m@samsung.com): Not all <length> properties have 0 (with no unit) as the default (lacuna) value, Need to return default value or previous valid value instead of 0

[Erik Dahlström (inactive), 2015/04/02 13:37:25]

Returning the previous value would be entirely wrong.

[Shanmuga Pandi, 2015/04/02 13:43:57]

I have checked the behavior in gecko with the following code.

document.querySelector("#svg").width.baseVal.valueAsString = "100px";
document.querySelector("#svg").width.baseVal.valueAsString = "1asda";

document.body.innerHTML += "<br> svg.width=" +
document.querySelector("#svg").width.baseVal.valueAsString;

gecko returns "100px" which is previous value, rather than default value "100%".

I wonder which behavior is correct? If you really feel, it is completely wrong,
let me know I will correct it. Thanks.

+    return hasExposedLengthUnit() ? target()->valueAsString() : String::number(0);
 }
 
 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 to 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)
 {
 }
 
 }