correct meta keys in correctModifierKeys, see #1625

js/accessibility/KeyStateTracker.ts

@@ -94,6 +94,9 @@ class KeyStateTracker {
         if ( assert && !KeyboardUtils.isControlKey( domEvent ) ) {
           assert( domEvent.ctrlKey === this.ctrlKeyDown, 'ctrl key inconsistency between event and keyState.' );
         }
+        if ( assert && !KeyboardUtils.isMetaKey( domEvent ) ) {
+          assert( domEvent.metaKey === this.metaKeyDown, 'meta key inconsistency between event and keyState.' );
+        }
 
         // if the key is already down, don't do anything else (we don't want to create a new keyState object
         // for a key that is already being tracked and down)
@@ -210,6 +213,13 @@ class KeyStateTracker {
         timeDown: 0 // in ms
       };
     }
+    if ( domEvent.metaKey && !KeyboardUtils.isMetaKey( domEvent ) && !this.metaKeyDown ) {
+      this.keyState[ KeyboardUtils.KEY_META_LEFT ] = {
+        keyDown: true,
+        key: key,
+        timeDown: 0 // in ms
+      };
+    }
 
     // delete modifier keys if we think they are down
     if ( !domEvent.shiftKey && this.shiftKeyDown ) {
@@ -224,6 +234,9 @@ class KeyStateTracker {
       delete this.keyState[ KeyboardUtils.KEY_CONTROL_LEFT ];
       delete this.keyState[ KeyboardUtils.KEY_CONTROL_RIGHT ];
     }
+    if ( !domEvent.metaKey && this.metaKeyDown ) {
+      KeyboardUtils.META_KEYS.forEach( key => { delete this.keyState[ key ]; } );
+    }
   }
 
   /**
@@ -392,6 +405,13 @@ class KeyStateTracker {
     return this.isAnyKeyInListDown( KeyboardUtils.CONTROL_KEYS );
   }
 
+  /**
+   * Returns true if one of the meta keys is currently down.
+   */
+  public get metaKeyDown(): boolean {
+    return this.isAnyKeyInListDown( KeyboardUtils.META_KEYS );
+  }
+
   /**
    * Returns the amount of time that the provided key has been held down. Error if the key is not currently down.
    * @param key - KeyboardEvent.code for the key you are inspecting.