[SVG2] Add support for the 'turn' unit in <angle>.

Source/core/svg/SVGAngleTearOff.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 91 matching lines @@
 }
 
 void SVGAngleTearOff::setValueAsString(const String& value, ExceptionState& exceptionState)
 {
     if (isImmutable()) {
         exceptionState.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
 
     target()->setValueAsString(value, exceptionState);
+
+    if (!exceptionState.hadException() && !isValidAngle()) {
+        exceptionState.throwDOMException(SyntaxError, "The value provided ('" + value + "') is invalid.");

[fs, 2014/06/10 11:13:30]

Hmm, the "damage" has been done here already (state modified). Save and
rollback?

[krit, 2014/06/10 11:45:48]

Does unknown unit type need to imply that we do not support the unit as string
in general? Internally we still do after all.

It is logical to not accept it and would be more consistent either I guess.

[Erik Dahlström (inactive), 2014/06/10 16:57:42]

If we want to behave as if the "turn" unit wasn't supported to a user of the
SVGAngle DOM interface then this is necessary. My preference is still that we
should follow the existing architecture of SVGAngle (extending it with the new
IDL constant), and then deprecating the whole interface as soon as we have a
proper replacement API (if any).
I don't fully understand what you mean.

[Erik Dahlström (inactive), 2014/06/10 16:57:42]

Done.

+        return;
+    }
+
     commitChange();
 }
 
 }