Move String#isWhitespace from the String prototype to a utiltiy function

R=jacktfranklin@chromium.org

Bug: chromium:1050549
Change-Id: Ief2e7c72d6faecd3849e66cfc7300891e22055b3
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2080372
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>

front_end/elements/ClassesPaneWidget.js

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import * as Common from '../common/common.js';
+import * as Platform from '../platform/platform.js';
 import * as SDK from '../sdk/sdk.js';
 import * as UI from '../ui/ui.js';
 
@@ -69,7 +70,7 @@ export class ClassesPaneWidget extends UI.Widget.Widget {
 
     let text = event.target.textContent;
     if (isEscKey(event)) {
-      if (!text.isWhitespace()) {
+      if (!Platform.StringUtilities.isWhitespace(text)) {
         event.consume(true);
       }
       text = '';

front_end/elements/ElementsTreeElement.js

@@ -31,6 +31,7 @@
 import * as Common from '../common/common.js';
 import * as Components from '../components/components.js';
 import * as Host from '../host/host.js';
+import * as Platform from '../platform/platform.js';
 import * as ProtocolModule from '../protocol/protocol.js';  // eslint-disable-line no-unused-vars
 import * as SDK from '../sdk/sdk.js';
 import * as TextUtils from '../text_utils/text_utils.js';
@@ -1023,7 +1024,7 @@ export class ElementsTreeElement extends UI.TreeOutline.TreeElement {
           }
         }
       } else if (moveDirection === 'forward') {
-        if (!newText.isWhitespace()) {
+        if (!Platform.StringUtilities.isWhitespace(newText)) {
           this._addNewAttribute();
         } else {
           this._startEditingTagName();

front_end/elements/StylePropertyTreeElement.js

@@ -5,6 +5,7 @@
 import * as ColorPicker from '../color_picker/color_picker.js';
 import * as Common from '../common/common.js';
 import * as InlineEditor from '../inline_editor/inline_editor.js';
+import * as Platform from '../platform/platform.js';
 import * as SDK from '../sdk/sdk.js';
 import * as TextUtils from '../text_utils/text_utils.js';
 import * as UI from '../ui/ui.js';
@@ -973,7 +974,7 @@ export class StylePropertyTreeElement extends UI.TreeOutline.TreeElement {
 
     // Make the Changes and trigger the moveToNextCallback after updating.
     let moveToIndex = moveTo && this.treeOutline ? this.treeOutline.rootElement().indexOfChild(moveTo) : -1;
-    const blankInput = userInput.isWhitespace();
+    const blankInput = Platform.StringUtilities.isWhitespace(userInput);
     const shouldCommitNewProperty = this._newProperty &&
         (isPropertySplitPaste || moveToOther || (!moveDirection && !isEditingName) || (isEditingName && blankInput) ||
          nameValueEntered);
@@ -982,7 +983,8 @@ export class StylePropertyTreeElement extends UI.TreeOutline.TreeElement {
       let propertyText;
       if (nameValueEntered) {
         propertyText = this.nameElement.textContent;
-      } else if (blankInput || (this._newProperty && this.valueElement.textContent.isWhitespace())) {
+      } else if (
+          blankInput || (this._newProperty && Platform.StringUtilities.isWhitespace(this.valueElement.textContent))) {
         propertyText = '';
       } else {
         if (isEditingName) {

front_end/formatter_worker/HTMLFormatter.js

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import * as Platform from '../platform/platform.js';
+
 import {CSSFormatter} from './CSSFormatter.js';
 import {FormattedContentBuilder} from './FormattedContentBuilder.js';  // eslint-disable-line no-unused-vars
 import {AbortTokenization, createTokenizer} from './FormatterWorker.js';
@@ -106,7 +108,7 @@ export class HTMLFormatter {
    * @param {!Token} token
    */
   _formatToken(element, token) {
-    if (token.value.isWhitespace()) {
+    if (Platform.StringUtilities.isWhitespace(token.value)) {
       return;
     }
     if (token.type.has('comment') || token.type.has('meta')) {

front_end/platform/string-utilities.js

@@ -304,3 +304,11 @@ export const findLineEndingIndexes = inputString => {
   endings.push(inputString.length);
   return endings;
 };
+
+/**
+ * @param {string} inputString
+ * @return {boolean}
+ */
+export const isWhitespace = inputString => {
+  return /^\s*$/.test(inputString);
+};

front_end/platform/utilities.js

@@ -64,13 +64,6 @@ String.prototype.replaceControlCharacters = function() {
   return this.replace(/[\0-\x08\x0B\f\x0E-\x1F\x80-\x9F]/g, '\uFFFD');
 };
 
-/**
- * @return {boolean}
- */
-String.prototype.isWhitespace = function() {
-  return /^\s*$/.test(this);
-};
-
 /**
  * @param {string} chars
  * @return {string}

test/unittests/front_end/platform/string-utilities.ts

@@ -60,4 +60,15 @@ describe('StringUtilities', () => {
       assert.deepEqual(indexes, [4, 7, 10, 12]);
     });
   });
+
+  describe('isWhitespace', () => {
+    it('correctly recognizes different kinds of whitespace', () => {
+      assert.isTrue(StringUtilities.isWhitespace(''));
+      assert.isTrue(StringUtilities.isWhitespace('  '));
+      assert.isTrue(StringUtilities.isWhitespace('\t'));
+      assert.isTrue(StringUtilities.isWhitespace('\n'));
+
+      assert.isFalse(StringUtilities.isWhitespace('  foo '));
+    });
+  });
 });