DevTools: Migrate General tab settings to extensions

Source/devtools/front_end/helpScreen.css

 .help-window-outer {
     position: absolute !important;
     top: 0;
     left: 0;
     right: 0;
     bottom: 0;
     z-index: 2000;
 }
 
 .help-window-main {
@@ skipping 114 matching lines @@
     -webkit-column-width: 410px;
 }
 
 .settings-tab .help-block {
     width: 410px;
     margin-left: 20px;
 }
 
 .settings-tab .field-error-message {
     color: DarkRed;
+    height: 0px; // Avoid changing element height when content is set.
 }
 
 .help-line {
     padding-bottom: 5px;
     margin-bottom: 5px;
 }
 
 .help-key-cell {
     display: inline-block;
     width: 270px;
@@ skipping 527 matching lines @@
 }
 
 .help-field-note {
     opacity: 0.6;
     padding-left: 19px;
 }
 
 .edit-file-system-dialog .section {
     min-width: 400px;
 }