Hoist some pre-condition checks out of SVGAngle/SVGEnumeration

third_party/WebKit/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 79 matching lines @@
     if (isImmutable()) {
         exceptionState.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
 
     if (unitType == SVGAngle::SVG_ANGLETYPE_UNKNOWN || unitType > SVGAngle::SVG_ANGLETYPE_GRAD) {
         exceptionState.throwDOMException(NotSupportedError, "Cannot convert to unknown or invalid units (" + String::number(unitType) + ").");
         return;
     }
 
-    target()->convertToSpecifiedUnits(static_cast<SVGAngle::SVGAngleType>(unitType), exceptionState);
-    if (!exceptionState.hadException())
-        commitChange();
+    if (target()->unitType() == SVGAngle::SVG_ANGLETYPE_UNKNOWN) {
+        exceptionState.throwDOMException(NotSupportedError, "Cannot convert from unknown or invalid units.");
+        return;
+    }
+
+    target()->convertToSpecifiedUnits(static_cast<SVGAngle::SVGAngleType>(unitType));
+    commitChange();
 }
 
 void SVGAngleTearOff::setValueAsString(const String& value, ExceptionState& exceptionState)
 {
     if (isImmutable()) {
         exceptionState.throwDOMException(NoModificationAllowedError, "The attribute is read-only.");
         return;
     }
 
     String oldValue = target()->valueAsString();
 
     target()->setValueAsString(value, exceptionState);
 
     if (!exceptionState.hadException() && !hasExposedAngleUnit()) {
         target()->setValueAsString(oldValue, ASSERT_NO_EXCEPTION); // rollback to old value
         exceptionState.throwDOMException(SyntaxError, "The value provided ('" + value + "') is invalid.");
         return;
     }
 
     commitChange();
 }
 
 }