Update to latest version of dom-seek

The previous version of dom-seek included untranspiled source and
provided Browserify transform configuration for an older version of
Babelify, which is incompatible with the version being used to transform
the client's main source.

The latest dom-seek release ships pre-transpiled code which doesn't have
this problem.

package.json

@@ -37,7 +37,7 @@
     "dom-anchor-fragment": "^1.0.1",
     "dom-anchor-text-position": "^4.0.0",
     "dom-anchor-text-quote": "^4.0.2",
-    "dom-seek": "^1.0.1",
+    "dom-seek": "^4.0.3",
     "end-of-stream": "^1.1.0",
     "escape-html": "^1.0.3",
     "escape-string-regexp": "^1.0.5",

yarn.lock

@@ -1829,11 +1829,7 @@ dom-node-iterator@^3.5.0:
   version "3.5.3"
   resolved "https://registry.yarnpkg.com/dom-node-iterator/-/dom-node-iterator-3.5.3.tgz#32b68aa440962f1734487029f544a3db704637b7"
 
-dom-seek@^1.0.1:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/dom-seek/-/dom-seek-1.0.1.tgz#7311112487e775f45c0acf7f336b2d58d0c232ba"
-
-dom-seek@^4.0.1:
+dom-seek@^4.0.1, dom-seek@^4.0.3:
   version "4.0.3"
   resolved "https://registry.yarnpkg.com/dom-seek/-/dom-seek-4.0.3.tgz#f14dddf04b3fb062d901c7b00b0c142a06e0a94b"
   dependencies: