Install wicked-good-xpath dependency from npm

This makes it easier to see what version we are using and get
automated notifications if the package is updated for any reason.

 - Update to current release of wicked-good-xpath from npm
 - Remove reference to IE 10 in comment since we now only support IE 11

package.json

@@ -107,6 +107,7 @@
     "vinyl": "^2.2.0",
     "watchify": "^3.7.0",
     "websocket": "^1.0.22",
+    "wicked-good-xpath": "^1.3.0",
     "wrap-text": "^1.0.7",
     "zen-observable": "^0.3.0"
   },

src/annotator/index.js

@@ -5,15 +5,10 @@ require('../shared/polyfills');
 
 // Polyfills
 
-// document.evaluate() implementation,
-// required by IE 10, 11
-//
-// This sets `window.wgxpath`
+// `document.evaluate` polyfill for IE 11.
 if (!window.document.evaluate) {
-  require('./vendor/wgxpath.install');
-}
-if (window.wgxpath) {
-  window.wgxpath.install();
+  const wgxpath = require('wicked-good-xpath');
+  wgxpath.install();
 }
 
 const $ = require('jquery');

yarn.lock

@@ -9324,13 +9324,25 @@ which@1, which@1.3.1, which@^1.2.10, which@^1.2.14, which@^1.2.9:
   dependencies:
     isexe "^2.0.0"
 
-wide-align@1.1.3, wide-align@^1.1.0:
+wicked-good-xpath@^1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/wicked-good-xpath/-/wicked-good-xpath-1.3.0.tgz#81b0e95e8650e49c94b22298fff8686b5553cf6c"
+  integrity sha1-gbDpXoZQ5JyUsiKY//hoa1VTz2w=
+
+wide-align@1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/wide-align/-/wide-align-1.1.3.tgz#ae074e6bdc0c14a431e804e624549c633b000457"
   integrity sha512-QGkOQc8XL6Bt5PwnsExKBPuMKBxnGxWWW3fU55Xt4feHozMUhdUMaBCk290qpm/wG5u/RSKzwdAC4i51YigihA==
   dependencies:
     string-width "^1.0.2 || 2"
 
+wide-align@^1.1.0:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/wide-align/-/wide-align-1.1.2.tgz#571e0f1b0604636ebc0dfc21b0339bbe31341710"
+  integrity sha512-ijDLlyQ7s6x1JgCLur53osjm/UXUYD9+0PbYKrBsYisYXzCxN+HC3mYDNy/dWdmf3AwqwU3CXwDCvsNgGK1S0w==
+  dependencies:
+    string-width "^1.0.2"
+
 windows-release@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/windows-release/-/windows-release-3.1.0.tgz#8d4a7e266cbf5a233f6c717dac19ce00af36e12e"