MC-4014: PageBuilder Performance Is Bad With Minimal Content

- Load TinyMCE within slides on click
- Fix tooltip text colour

Author: davemacaulay

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/slider/_default.less

@@ -102,6 +102,7 @@
                     border-radius: 1px;
                     bottom: 97.5%;
                     box-shadow: 0 2px 8px 0 rgba(0, 0, 0, .3);
+                    color: @color-pagebuilder-darkest-gray;
                     font-size: 14px;
                     left: 50%;
                     min-width: auto;

app/code/Magento/PageBuilder/view/adminhtml/web/js/content-type/slide/preview.js

@@ -26,8 +26,9 @@
                      attr="data.content.attributes"
                      ko-style="data.content.style"
                      css="data.content.css"
-                     event="mousedown: stopEvent"
-                     afterRender="initWysiwyg">
+                     event="mousedown: stopEvent, click: activateEditor"
+                     contenteditable="true"
+                     afterRender="afterRenderWysiwyg">
                     <div html="data.content.html"></div>
                 </div>
                 <div if="!data.content.html() && isWysiwygSupported()"