[DevTools] Adjust popover position so accomodate for arrow.

third_party/WebKit/Source/devtools/front_end/ui/GlassPane.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 UI.GlassPane = class {
   constructor() {
     this._widget = new UI.Widget(true);
     this._widget.markAsRoot();
     this.element = this._widget.element;
     this.contentElement = this._widget.contentElement;
@@ skipping 216 matching lines @@
             }
           } else {
             height = Math.min(height, spaceBottom);
           }
           this._arrowElement.setIconType('mediumicon-arrow-top');
           this._arrowElement.classList.add('arrow-top');
           arrowY = anchorBox.y + anchorBox.height + gutterSize;
         }
 
         positionX = Math.max(gutterSize, Math.min(anchorBox.x, containerWidth - width - gutterSize));
+        if (this._showArrow && positionX - arrowSize >= gutterSize)
+          positionX -= arrowSize;
         width = Math.min(width, containerWidth - positionX - gutterSize);
         if (2 * arrowSize >= width) {
           this._arrowElement.classList.add('arrow-none');
         } else {
           var arrowX = anchorBox.x + Math.min(50, Math.floor(anchorBox.width / 2));
           arrowX = Number.constrain(arrowX, positionX + arrowSize, positionX + width - arrowSize);
           this._arrowElement.positionAt(arrowX, arrowY, container);
         }
       } else {
         var left = anchorBox.x - 2 * gutterSize;
@@ skipping 30 matching lines @@
             }
           } else {
             width = Math.min(width, spaceRight);
           }
           this._arrowElement.setIconType('mediumicon-arrow-left');
           this._arrowElement.classList.add('arrow-left');
           arrowX = anchorBox.x + anchorBox.width + gutterSize;
         }
 
         positionY = Math.max(gutterSize, Math.min(anchorBox.y, containerHeight - height - gutterSize));
+        if (this._showArrow && positionY - arrowSize >= gutterSize)
+          positionY -= arrowSize;
         height = Math.min(height, containerHeight - positionY - gutterSize);
         if (2 * arrowSize >= height) {
           this._arrowElement.classList.add('arrow-none');
         } else {
           var arrowY = anchorBox.y + Math.min(50, Math.floor(anchorBox.height / 2));
           arrowY = Number.constrain(arrowY, positionY + arrowSize, positionY + height - arrowSize);
           this._arrowElement.positionAt(arrowX, arrowY, container);
         }
       }
     } else {
@@ skipping 72 matching lines @@
   SetExactSize: Symbol('SetExactSize'),
   SetMaxSize: Symbol('SetMaxSize'),
   SetExactWidthMaxHeight: Symbol('SetExactWidthMaxHeight'),
   MeasureContent: Symbol('MeasureContent')
 };
 
 /** @type {!Map<!Document, !Element>} */
 UI.GlassPane._containers = new Map();
 /** @type {!Set<!UI.GlassPane>} */
 UI.GlassPane._panes = new Set();