Handle a bad XSLT expression better.

third_party/libxslt/libxslt/pattern.c

 /*
  * pattern.c: Implemetation of the template match compilation and lookup
  *
  * Reference:
  *   http://www.w3.org/TR/1999/REC-xslt-19991116
  *
  * See Copyright for the status of this software.
  *
  * daniel@veillard.com
  */
@@ skipping 1769 matching lines @@
         name = xsltScanNCName(ctxt);
         if (name == NULL) {
             xsltTransformError(NULL, NULL, NULL,
                     "xsltCompileLocationPathPattern : Name expected\n");
             ctxt->error = 1;
             return;
         }
         SKIP_BLANKS;
         if ((CUR == '(') && !xmlXPathIsNodeType(name)) {
             xsltCompileIdKeyPattern(ctxt, name, 1, novar, 0);
+            if (ctxt->error)
+                return;
             if ((CUR == '/') && (NXT(1) == '/')) {
                 PUSH(XSLT_OP_ANCESTOR, NULL, NULL, novar);
                 NEXT;
                 NEXT;
                 SKIP_BLANKS;
                 xsltCompileRelativePathPattern(ctxt, NULL, novar);
             } else if (CUR == '/') {
                 PUSH(XSLT_OP_PARENT, NULL, NULL, novar);
                 NEXT;
                 SKIP_BLANKS;
@@ skipping 702 matching lines @@
     if (style->parentMatch != NULL)
         xsltFreeCompMatchList(style->parentMatch);
     if (style->textMatch != NULL)
         xsltFreeCompMatchList(style->textMatch);
     if (style->piMatch != NULL)
         xsltFreeCompMatchList(style->piMatch);
     if (style->commentMatch != NULL)
         xsltFreeCompMatchList(style->commentMatch);
 }