Remove support for the externalResourcesRequired attribute.

LayoutTests/svg/W3C-SVG-1.1-SE/types-dom-04-b.svg

 <svg id="svg-root" width="100%" height="100%"
   viewBox="0 0 480 360" xmlns="http://www.w3.org/2000/svg"
   xmlns:xlink="http://www.w3.org/1999/xlink">
   <!--======================================================================-->
   <!--=  Copyright 2008 World Wide Web Consortium, (Massachusetts          =-->
   <!--=  Institute of Technology, European Research Consortium for         =-->
   <!--=  Informatics and Mathematics (ERCIM), Keio University).            =-->
   <!--=  All Rights Reserved.                                              =-->
   <!--=  See http://www.w3.org/Consortium/Legal/.                          =-->
   <!--======================================================================-->
@@ skipping 70 matching lines @@
       <rect id='r11' x='40' y='360' width='20' height='20'/>
       <text x='70' y='375'>SVGAnimatedInteger</text>
       <rect id='r12' x='40' y='390' width='20' height='20'/>
       <text x='70' y='405'>SVGAnimatedNumber</text>
     </g>
 
     <g display='none'>
       <text id='text' rotate='0 20 40' x='10 20' lengthAdjust='spacing'>abc</text>
       <circle id='circle' r='50' transform='scale(1) scale(2)' class='one'/>
       <marker id='marker' orient='30'/>
-      <svg id='svg' viewBox='10 20 30 40' preserveAspectRatio='none' externalResourcesRequired='false'/>
+      <svg id='svg' viewBox='10 20 30 40' preserveAspectRatio='none'/>
       <filter>
         <feTurbulence id='feTurbulence' baseFrequency='2 3' numOctaves='2'/>
+        <feConvolveMatrix id='feConvolveMatrix' kernelMatrix='1 1 1
+                                                                                                                          1 1 1
+                                                                                                                          1 1 1' preserveAlpha='false'/>
       </filter>
     </g>
 
     <script><![CDATA[
       function $(id) { return document.getElementById(id); }
 
       var text = $('text'),
           circle = $('circle'),
           marker = $('marker'),
           svg = $('svg'),
-          feTurbulence = $('feTurbulence');
+          feTurbulence = $('feTurbulence'),
+          feConvolveMatrix = $('feConvolveMatrix');
 
       function expect_exception(id, fn, code) {
         try {
           fn();
         } catch (e) {
           if (e.code == code) {
             $(id).setAttribute('fill', 'green');
             return;
           }
         }
@@ skipping 67 matching lines @@
 
       // SVGAnimatedPreserveAspectRatio: preserveAspectRatio on svg
       expect_value
         ('r7',
          function() {
            return svg.preserveAspectRatio.baseVal.align == 1 /* none */
                && (svg.setAttribute('preserveAspectRatio', 'xMidYMid'), svg.preserveAspectRatio.baseVal.align == 6);
          },
          true);
 
-      // SVGAnimatedBoolean: externalResourcesRequired on svg
+      // SVGAnimatedBoolean: preserveAlpha on feConvolveMatrix
       expect_value
         ('r8',
          function() {
-           return !svg.externalResourcesRequired.baseVal
-               && (svg.setAttribute('externalResourcesRequired', 'true'), svg.externalResourcesRequired.baseVal);
+           return !feConvolveMatrix.preserveAlpha.baseVal
+               && (feConvolveMatrix.setAttribute('preserveAlpha', 'true'), feConvolveMatrix.preserveAlpha.baseVal);
          },
          true);
 
       // SVGAnimatedString: class on circle
       expect_value
         ('r9',
          function() {
            return circle.className.baseVal == 'one'
                && (circle.setAttribute('class', 'two'), circle.className.baseVal == 'two');
          },
@@ skipping 33 matching lines @@
       fill="black">$Revision: 1.7 $</text>
   </g>
   <rect id="test-frame" x="1" y="1" width="478" height="358" fill="none" stroke="#000"/>
   <!-- comment out this watermark once the test is approved --><!--
   <g id="draft-watermark">
     <rect x="1" y="1" width="478" height="20" fill="red" stroke="black" stroke-width="1"/>
     <text font-family="SVGFreeSansASCII,sans-serif" font-weight="bold" font-size="20" x="240"
       text-anchor="middle" y="18" stroke-width="0.5" stroke="black" fill="white">DRAFT</text>
   </g>-->
 </svg>