Add pointer-events="bounding-box" for svg content.

Source/devtools/front_end/CSSMetadata.js

 /*
  * Copyright (C) 2010 Nikita Vasilyev. All rights reserved.
  * Copyright (C) 2010 Joseph Pecoraro. All rights reserved.
  * Copyright (C) 2010 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
@@ skipping 438 matching lines @@
     "max-width": { values: [
         "none"
     ] },
     "caption-side": { values: [
         "top", "bottom"
     ] },
     "empty-cells": { values: [
         "hide", "show"
     ] },
     "pointer-events": { values: [
-        "none", "all", "auto", "visible", "visiblepainted", "visiblefill", "visiblestroke", "painted", "fill", "stroke"
+        "none", "all", "auto", "visible", "visiblepainted", "visiblefill", "visiblestroke", "painted", "fill", "stroke", "boundingbox"
     ] },
     "letter-spacing": { values: [
         "normal"
     ] },
     "background-clip": { values: [
         "border-box", "content-box", "padding-box"
     ] },
     "-webkit-font-smoothing": { values: [
         "none", "auto", "antialiased", "subpixel-antialiased"
     ] },
@@ skipping 500 matching lines @@
 
     /**
      * @param {string} longhand
      * @return {?Array.<string>}
      */
     shorthands: function(longhand)
     {
         return this._shorthands[longhand];
     }
 }