SVG12TextElementBridge performs cast without instanceof

Re: https://issues.apache.org/jira/browse/BATIK-1302

@carlosame notes:

The proper fix would be a major refactor: the code is asking for it, especially the CSSOM part (already did a small one there, but far from enough). Meanwhile a smaller fix would be of help.

The smaller, simple fix in the interim is to add an instanceof check to In SVG12TextElementBridge, around line 67, like:

if( ctx instanceof SVG12BridgeContext ) {
   ctx12 = (SVG12BridgeContext) ctx;
}

[carlosame]

I'm thinking of something like this:

@@ -54,10 +54,16 @@ public class SVG12TextElementBridge extends SVGTextElementBridge implements SVG1
 	/**
 	 * Adds the DOM listeners for this text bridge.
 	 */
 	@Override
 	protected void addTextEventListeners(BridgeContext ctx, NodeEventTarget e) {
+		if (!(ctx instanceof SVG12BridgeContext)) {
+			// SVG 1.2 text element inside 1.1 document
+			super.addTextEventListeners(ctx, e);
+			return;
+		}
+
 		if (childNodeRemovedEventListener == null) {
 			childNodeRemovedEventListener = new DOMChildNodeRemovedEventListener();
 		}
 		if (subtreeModifiedEventListener == null) {
 			subtreeModifiedEventListener = new DOMSubtreeModifiedEventListener();