De-ExceptionState-ify SVGLengthContext

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 4706375632785d7d0968c17400b926015bf833b3..d02e2608fa68b6d693ef0dec48f382d3022949d3 100644
--- a/Source/core/svg/SVGLengthTearOff.cpp
+++ b/Source/core/svg/SVGLengthTearOff.cpp
@@ -46,6 +46,11 @@ inline SVGLengthType toSVGLengthType(unsigned short type)
     return static_cast<SVGLengthType>(type);
 }
 
+inline bool canResolveRelativeUnits(const SVGElement* contextElement)
+{
+    return contextElement && contextElement->inDocument();
+}
+
 } // namespace
 
 SVGLengthType SVGLengthTearOff::unitType()
@@ -58,21 +63,31 @@ SVGLengthMode SVGLengthTearOff::unitMode()
     return target()->unitMode();
 }
 
-float SVGLengthTearOff::value(ExceptionState& es)
+float SVGLengthTearOff::value(ExceptionState& exceptionState)
 {
+    if (target()->isRelative() && !canResolveRelativeUnits(contextElement())) {
+        exceptionState.throwDOMException(NotSupportedError, "No context could be found.");
+        return 0;
+    }
+
     SVGLengthContext lengthContext(contextElement());
-    return target()->value(lengthContext, es);
+    return target()->value(lengthContext);
 }
 
-void SVGLengthTearOff::setValue(float value, ExceptionState& es)
+void SVGLengthTearOff::setValue(float value, ExceptionState& exceptionState)
 {
     if (isImmutable()) {
-        es.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
+        exceptionState.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
+        return;
+    }
+
+    if (target()->isRelative() && !canResolveRelativeUnits(contextElement())) {
+        exceptionState.throwDOMException(NotSupportedError, "No context could be found.");
         return;
     }
 
     SVGLengthContext lengthContext(contextElement());
-    target()->setValue(value, lengthContext, es);
+    target()->setValue(value, lengthContext);
     commitChange();
 }
 
@@ -135,8 +150,14 @@ void SVGLengthTearOff::convertToSpecifiedUnits(unsigned short unitType, Exceptio
         return;
     }
 
+    if ((target()->isRelative() || SVGLength::isRelativeUnit(toSVGLengthType(unitType)))
+        && !canResolveRelativeUnits(contextElement())) {
+        exceptionState.throwDOMException(NotSupportedError, "No context could be found.");

[pdr., 2015/02/05 22:12:32]

Bikeshed: is the concept of a length context something users would know about?
We may just want to say "Could not resolve relative length".

[fs, 2015/02/06 12:26:04]

Funny you should say that, because that's pretty much what I intended to change
it too before I decided to be lazy... =P

+        return;
+    }
+
     SVGLengthContext lengthContext(contextElement());
-    target()->convertToSpecifiedUnits(toSVGLengthType(unitType), lengthContext, exceptionState);
+    target()->convertToSpecifiedUnits(toSVGLengthType(unitType), lengthContext);
     commitChange();
 }