MDL-65581 core_blocks: change classname for hidden blocks

Changing the added class .invisible to .ivisibleblock to avoid hiding
the block completely

blocks/moodleblock.class.php

@@ -232,7 +232,7 @@ class block_base {
                 $bc->footer = $this->content->footer;
             }
         } else {
-            $bc->add_class('invisible');
+            $bc->add_class('invisibleblock');
         }
 
         if (!$this->hide_header()) {

theme/boost/scss/moodle/blocks.scss

@@ -297,4 +297,8 @@ body.drawer-open-left #region-main.has-blocks {
     .icon {
         margin-right: 2px;
     }
+}
+
+.block.invisibleblock .card-title {
+    color: $text-muted;
 }

theme/boost/style/moodle.css

@@ -11386,6 +11386,9 @@ div.editor_atto_toolbar button .icon {
   .block_settings .block_tree p.hasicon .icon {
     margin-right: 2px; }
 
+.block.invisibleblock .card-title {
+  color: #868e96; }
+
 .navbar {
   max-height: 50px; }
 

theme/bootstrapbase/less/moodle/blocks.less

@@ -72,7 +72,7 @@
         border-width: 2px;
         border-style: dashed;
     }
-    &.invisible {
+    &.invisibleblock {
         .header h2 {
             .opacity(50);
         }

theme/bootstrapbase/style/moodle.css

@@ -16229,7 +16229,7 @@ body {
   border-width: 2px;
   border-style: dashed;
 }
-.block.invisible .header h2 {
+.block.invisibleblock .header h2 {
   opacity: 0.5;
   filter: alpha(opacity=50);
 }