SVG doesn't recognize rem units

Source/core/svg/SVGLengthTearOff.cpp

Index: Source/core/svg/SVGLengthTearOff.cpp
diff --git a/Source/core/svg/SVGLengthTearOff.cpp b/Source/core/svg/SVGLengthTearOff.cpp
index e43a606269c486143342e911471eff1a46cbf7b6..88eefe79623908eb0835d73f8e78b9f80f4dd6f6 100644
--- a/Source/core/svg/SVGLengthTearOff.cpp
+++ b/Source/core/svg/SVGLengthTearOff.cpp
@@ -55,7 +55,7 @@ inline bool canResolveRelativeUnits(const SVGElement* contextElement)
 
 SVGLengthType SVGLengthTearOff::unitType()
 {
-    return target()->unitType();
+    return hasExposedLengthUnit() ? target()->unitType() : LengthTypeUnknown;
 }
 
 SVGLengthMode SVGLengthTearOff::unitMode()
@@ -108,7 +108,8 @@ void SVGLengthTearOff::setValueInSpecifiedUnits(float value, ExceptionState& es)
 
 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)
@@ -118,7 +119,16 @@ void SVGLengthTearOff::setValueAsString(const String& str, ExceptionState& es)
         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();
 }