Bug 1461522 - Persist active styles for a button with an expanded menu; r=jdescottes

When we open the menu, the menu button should remain active so long as the menu
is open.

MozReview-Commit-ID: DPYEjbNiOuY

--HG--
extra : rebase_source : 47d44c326f012c45f988b3594c0fd15ddaa82365

devtools/client/themes/common.css

@@ -358,7 +358,7 @@ checkbox:-moz-focusring {
 }
 
 .devtools-toolbarbutton:not([label]):hover,
-.devtools-button:empty:not(:disabled):hover {
+.devtools-button:empty:not(:disabled):not([aria-expanded="true"]):hover {
   background: var(--toolbarbutton-background);
 }
 
@@ -371,7 +371,8 @@ checkbox:-moz-focusring {
 .devtools-button:not(:empty):not(:disabled):not(.checked):hover,
 .devtools-toolbarbutton[label]:not(:-moz-any([checked=true],[disabled])):hover,
 .devtools-button:empty:not(:disabled):-moz-any(:hover:active,.checked),
-.devtools-toolbarbutton:not([label]):-moz-any([checked],[open],:hover:active) {
+.devtools-toolbarbutton:not([label]):-moz-any([checked],[open],:hover:active),
+.devtools-button[aria-haspopup="menu"][aria-expanded="true"] {
   background: var(--toolbarbutton-hover-background);
   border-color: var(--toolbarbutton-hover-border-color);
 }