Added support of calc() for SVGLength

third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp

Index: third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp b/third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp
index ebff1f65177f326445c48f10344a3d3bf6ab2c7d..54756245713394f0e8dcdbf7fe4d3b0fc15572da 100644
--- a/third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGLengthTearOff.cpp
@@ -104,6 +104,9 @@ inline SVGLengthType toSVGLengthType(CSSPrimitiveValue::UnitType type)
 
 bool SVGLengthTearOff::hasExposedLengthUnit()
 {
+    if (target()->isCalculated())
+        return false;
+
     CSSPrimitiveValue::UnitType unit = target()->typeWithCalcResolved();
     return isValidLengthUnit(unit)
         || unit == CSSPrimitiveValue::UnitType::Unknown
@@ -144,12 +147,19 @@ void SVGLengthTearOff::setValue(float value, ExceptionState& exceptionState)
     }
 
     SVGLengthContext lengthContext(contextElement());
-    target()->setValue(value, lengthContext);
+    if (target()->isCalculated())
+        target()->setValueAsNumber(value);

[fs, 2016/07/16 21:13:02]

Per the other CL (and current spec text) this would be the only case necessary?

[Shanmuga Pandi, 2016/07/18 13:35:33]

As per the spec, It should always "Set the SVGLength's value to a <number> whose
value is value.".
Since my previous patch is reverted, I added just isCalculated() check to handle
calc cases. 
But eventually, it should be as per spec. I will investigate why that patch is
reverted, if I get the testCase.

[fs, 2016/07/18 13:56:48]

Fair enough.

+    else
+        target()->setValue(value, lengthContext);
+
     commitChange();
 }
 
 float SVGLengthTearOff::valueInSpecifiedUnits()
 {
+    if (target()->isCalculated())
+        return 0;
+
     return target()->valueInSpecifiedUnits();
 }
 
@@ -159,7 +169,12 @@ void SVGLengthTearOff::setValueInSpecifiedUnits(float value, ExceptionState& exc
         exceptionState.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
-    target()->setValueInSpecifiedUnits(value);
+
+    if (target()->isCalculated())
+        target()->setValueAsNumber(value);
+    else
+        target()->setValueInSpecifiedUnits(value);
+
     commitChange();
 }