Replace patchNum compare with utility function

In preparation for implementation of in-app editing, the instances of
parseInt(patchNum) must be swapped out, as a patchNum may now be either
a number or a string.

This change adds the patchNumEquals function to gr-patch-set-behavior,
and uses it everywhere patchNum is compared.

Bug: Issue 4437
Change-Id: Ib1176508cd88d60c79e952b99dd5f57b994baa77
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
index 70772b8..8bbb5c2 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
@@ -15,6 +15,7 @@
 -->
 
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../../behaviors/gr-patch-set-behavior/gr-patch-set-behavior.html">
 <link rel="import" href="../../../behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html">
 <link rel="import" href="../../../behaviors/rest-client-behavior/rest-client-behavior.html">
 <link rel="import" href="../../../bower_components/iron-dropdown/iron-dropdown.html">
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
index 168ec57..7181270 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
@@ -115,6 +115,7 @@
 
     behaviors: [
       Gerrit.KeyboardShortcutBehavior,
+      Gerrit.PatchSetBehavior,
       Gerrit.RESTClientBehavior,
     ],
 
@@ -714,11 +715,10 @@
      * @return {Promise} A promise that yields a comment map object.
      */
     _loadCommentMap() {
-      const filterByRange = comment => {
-        const patchNum = comment.patch_set + '';
-        return patchNum === this._patchRange.patchNum ||
-            patchNum === this._patchRange.basePatchNum;
-      };
+      const filterByRange = comment =>
+          this.patchNumEquals(comment.patch_set, this._patchRange.patchNum) ||
+            this.patchNumEquals(comment.patch_set,
+                this._patchRange.basePatchNum);
 
       return Promise.all([
         this.$.restAPI.getDiffComments(this._changeNum),