ChromeVox: Clean up style in tree_walker.js

This change:
1. Adds braces for all control structures according to the Google
JavaScript style guidelines: http://go/js-style.
2. Access the phase member variable (this.phase_) when checking
the current phase. The previous code was confusing because
sometimes we would check the tree walker phase using the getter
(this.phase) and other times we would directly check the member
variable (this.phase_).

Change-Id: Id2288716d7b1bb1a08fb8c06760a17a753be8081
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880178
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#714702}

chrome/browser/resources/chromeos/chromevox/background/tree_walker.js

@@ -93,13 +93,15 @@ AutomationTreeWalker = function(node, dir, opt_restrictions) {
 
   this.visitPred_ = function(node) {
     if (this.skipInitialAncestry_ &&
-        this.phase_ == AutomationTreeWalkerPhase.ANCESTOR)
+        this.phase_ == AutomationTreeWalkerPhase.ANCESTOR) {
       return false;
+    }
 
     if (this.skipInitialSubtree_ &&
-        this.phase != AutomationTreeWalkerPhase.ANCESTOR &&
-        this.phase != AutomationTreeWalkerPhase.OTHER)
+        this.phase_ != AutomationTreeWalkerPhase.ANCESTOR &&
+        this.phase_ != AutomationTreeWalkerPhase.OTHER) {
       return false;
+    }
 
     if (restrictions.visit) {
       return restrictions.visit(node);
@@ -174,7 +176,7 @@ AutomationTreeWalker.prototype = {
       }
 
       if (!this.skipInitialSubtree_ ||
-          this.phase != AutomationTreeWalkerPhase.DESCENDANT) {
+          this.phase_ != AutomationTreeWalkerPhase.DESCENDANT) {
         this.node_ = node.firstChild;
         return;
       }
@@ -201,8 +203,9 @@ AutomationTreeWalker.prototype = {
       // Exit if we encounter a root-like node and are not searching descendants
       // of the initial node.
       if (searchNode.parent && this.rootPred_(searchNode.parent) &&
-          this.phase_ != AutomationTreeWalkerPhase.DESCENDANT)
+          this.phase_ != AutomationTreeWalkerPhase.DESCENDANT) {
         break;
+      }
 
       searchNode = searchNode.parent;
     }
@@ -218,8 +221,9 @@ AutomationTreeWalker.prototype = {
       this.phase_ = AutomationTreeWalkerPhase.OTHER;
       node = node.previousSibling;
 
-      while (!this.leafPred_(node) && node.lastChild)
+      while (!this.leafPred_(node) && node.lastChild) {
         node = node.lastChild;
+      }
 
       this.node_ = node;
       return;