Bug 736846 - about:home launcher buttons jerk down as the icons load. r=mak

browser/base/content/abouthome/aboutHome.css

@@ -293,6 +293,7 @@ body[narrow] #restorePreviousSession {
 
 .launchButton::before {
   display: block;
+  height: 32px;
   margin-bottom: 6px;
   line-height: 0; /* remove extra vertical space due to non-zero font-size */
 }
@@ -323,6 +324,8 @@ body[narrow] #restorePreviousSession {
 
 #restorePreviousSession::before {
   content: url("chrome://browser/content/abouthome/restore-large.png");
+  height: 48px;
+  width: 48px;
   display: inline-block; /* display on same line as text label */
   vertical-align: middle;
   margin-bottom: 0;
@@ -335,6 +338,8 @@ body[dir=rtl] #restorePreviousSession::before {
 
 body[narrow] #restorePreviousSession::before {
   content: url("chrome://browser/content/abouthome/restore.png");
+  height: 32px;
+  width: 32px;
 }
 
 #aboutMozilla {