Bug 118351

Have SVGTextContentElement inherit SVGGraphicsElement instead of SVGStyledElement in order to match the latest SVG2 specification: https://svgwg.org/svg2-draft/text.html#InterfaceSVGTextContentElement This patch also removes the SVGTransformable and SVGLocatable IDL interfaces as they are no longer needed (were merged into SVGGraphicsElement in the latest specification). Conversion to absolute (user agent) coordinates in the svg/text tests is fixed to use SVGGraphicsElement::getScreenCTM() instead of SVGGraphicsElement::getTransformToElement(). The previous code was working until now due to a bug in getTransformToElement(), which was not taking into consideration the CTM of the SVGTextElement (as it was not recognized as a "locatable" element). Now that SVGTextElement inherits from SVGGraphicsElement, it is properly recognized as a "locatable" element by getTransformToElement(). This is one step towards getting rid of multiple inheritance in SVG and matching the latest SVG2 specification. Corresponding Blink revision: https://src.chromium.org/viewvc/blink?view=rev&revision=153432