Filter out whitespace-only nodes in speech during editable text feedback

Sometimes, we get inline text boxes containing only whitespace in the middle or end of a line.
This is typically fine if the whitespace is the only text. However, there are situations where we want this whitespace not to be queued.

When there is non-whitespace text in the line:
inLineTextBox: "this is a soft-wrap"
inLineTextBox.nextOnLine: " "
inLineTextBox: "of text"

becomes (for the first line):
"this is a soft-wrap", "space"

inlineTextBox: "this"
inLineTextBox.nextOnLine: " "
inLineTextBox.nextOnLine.nextOnLine: "is"

becomes
"this", "space", "is"

Test: manual.
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If8524c90f4187704bbf1dcfb5580e5697eedeccf
Reviewed-on: https://chromium-review.googlesource.com/1015657Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551767}

chrome/browser/resources/chromeos/chromevox/cvox2/background/editing.js

@@ -538,12 +538,17 @@ AutomationRichEditableText.prototype = {
     for (var i = 0, cur; cur = lineNodes[i]; i++) {
       if (cur.children.length)
         continue;
-      new Output()
+
+      var o = new Output()
                   .withRichSpeech(
                       Range.fromNode(cur), prev ? Range.fromNode(prev) : null,
                       Output.EventType.NAVIGATE)
-          .withQueueMode(queueMode)
-          .go();
+                  .withQueueMode(queueMode);
+
+      // Ignore whitespace only output except if it is leading content on the
+      // line.
+      if (!o.isOnlyWhitespace || i == 0)
+        o.go();
       prev = cur;
       queueMode = cvox.QueueMode.QUEUE;
     }

chrome/browser/resources/chromeos/chromevox/cvox2/background/output.js

@@ -679,6 +679,15 @@ Output.prototype = {
     return false;
   },
 
+  /**
+   * @return {boolean} True if there is only whitespace in this output.
+   */
+  get isOnlyWhitespace() {
+    return this.speechBuffer_.every(function(buff) {
+      return !/\S+/.test(buff.toString());
+    });
+  },
+
   /** @return {Spannable} */
   get braille() {
     return this.mergeBraille_(this.brailleBuffer_);