feat(menu): Remove obsolete pre-states styles; fix dark-mode selector (…

…#1739)

BREAKING CHANGE: the "mdc-simple-menu--selected" class is replaced by "mdc-list-item--selected", as it pertains to a specific list item and not the entire menu.

packages/mdc-menu/simple/mdc-simple-menu.scss

@@ -138,7 +138,6 @@ $mdc-simple-menu-item-fade-duration: .3s;
     }
 
     position: relative;
-    padding: 0 16px;
     outline: none;
     color: inherit;
     text-decoration: none;
@@ -159,52 +158,18 @@ $mdc-simple-menu-item-fade-duration: .3s;
     }
   }
 
-  // stylelint-disable selector-no-qualifying-type
-  &--selected.mdc-list-item,
-  &--selected.mdc-list-item .mdc-list-item__graphic {
-    @include mdc-theme-prop(color, primary);
-  }
-  // stylelint-enable selector-no-qualifying-type
-
-  // TODO(sgomes): Revisit when we have interactive lists.
-  .mdc-list-item::before {
-    position: absolute;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-    transition: opacity 120ms $mdc-animation-deceleration-curve-timing-function;
-    border-radius: inherit;
-    background: currentColor;
-    opacity: 0;
-    pointer-events: none;
-    content: "";
-  }
-
-  .mdc-list-item:focus::before {
-    opacity: .12;
-  }
-
-  .mdc-list-item:active::before {
-    // Slightly darker value for visual distinction.
-    // This allows a full base that has distinct modes.
-    // Progressive enhancement with ripples will provide complete button spec alignment.
-    opacity: .18;
-  }
-
   .mdc-list-item[aria-disabled="true"] {
     @include mdc-theme-prop(color, text-disabled-on-light);
 
-    @include mdc-theme-dark(".mdc-select") {
+    @include mdc-theme-dark(".mdc-simple-menu") {
       @include mdc-theme-prop(color, text-disabled-on-dark);
     }
 
     cursor: default;
-  }
+    pointer-events: none;
 
-  .mdc-list-item[aria-disabled="true"] {
-    &:focus::before,
-    &:active::before {
+    // TODO(#1495): Disabled menu items shouldn't be focusable, so this style shouldn't be necessary.
+    &:focus::before {
       opacity: 0;
     }
   }