Merge branch 't/11085'

Author: Reinmar

CHANGES.md

@@ -12,6 +12,7 @@ Fixed Issues:
 
 * [#11244](http://dev.ckeditor.com/ticket/11244): Changed: The [`widget.repository.checkWidgets`](http://docs.ckeditor.com/#!/api/CKEDITOR.plugins.widget.repository-method-checkWidgets) method now fires the [`widget.repository.checkWidgets`](http://docs.ckeditor.com/#!/api/CKEDITOR.plugins.widget.repository-event-checkWidgets) event, so from CKEditor 4.3.1 it's preferred to use method rather than fire event.
 * [#11171](http://dev.ckeditor.com/ticket/11171): Fixed: [`editor.insertElement`](http://docs.ckeditor.com/#!/api/CKEDITOR.editor-method-insertElement) and [`editor.insertText`](http://docs.ckeditor.com/#!/api/CKEDITOR.editor-method-insertText) methods do not call the [`widget.repository.checkWidgets`](http://docs.ckeditor.com/#!/api/CKEDITOR.plugins.widget.repository-method-checkWidgets) method.
+* [#11085](http://dev.ckeditor.com/ticket/11085): [IE8] Replaced preview generated by [Mathematical Formulas](http://ckeditor.com/addon/mathjax) widget with a placeholder.
 * [#11044](http://dev.ckeditor.com/ticket/11044): Enhanced aria support for language plugin drop-down menu.
 * [#11075](http://dev.ckeditor.com/ticket/11075): With drop-down menubutton focused, pressing down arrow key will now open menu and focus its first option.
 * [#11165](http://dev.ckeditor.com/ticket/11165): Fixed: The filebrowser plugin cannot be removed from the editor.

plugins/mathjax/dialogs/mathjax.js

@@ -26,18 +26,17 @@ CKEDITOR.dialog.add( 'mathjax', function( editor ) {
 						onLoad: function( widget ) {
 							var that = this;
 
-							this.getInputElement().on( 'keyup', function() {
-								// Add \( and \) for preview.
-								preview.setValue( '\\(' + that.getInputElement().getValue() + '\\)' );
-							} );
+							if ( !( CKEDITOR.env.ie && CKEDITOR.env.version == 8 ) ) {
+								this.getInputElement().on( 'keyup', function() {
+									// Add \( and \) for preview.
+									preview.setValue( '\\(' + that.getInputElement().getValue() + '\\)' );
+								} );
+							}
 						},
 
 						setup: function( widget ) {
 							// Remove \( and \).
-							var math = widget.data.math,
-								begin = math.indexOf( '\\(' ) + 2,
-								end = math.lastIndexOf( '\\)' );
-							this.setValue( math.substring( begin, end ) );
+							this.setValue( CKEDITOR.plugins.mathjax.trim( widget.data.math ) );
 						},
 
 						commit: function( widget ) {
@@ -55,7 +54,7 @@ CKEDITOR.dialog.add( 'mathjax', function( editor ) {
 								'</a>' +
 							'</div>'
 					},
-					{
+					( !( CKEDITOR.env.ie && CKEDITOR.env.version == 8 ) ) && {
 						id: 'preview',
 						type: 'html',
 						html: