Vendor prefix fixes from @redmunds and @TomMalbran

Author: larz0

src/styles/brackets.less

@@ -1300,7 +1300,9 @@ textarea.exclusions-editor {
     opacity: 0;
     .animation (autocomplete, 90ms, cubic-bezier(.01, .91, 0, .99), 0, 1);
     -webkit-animation-fill-mode: forwards;
+    animation-fill-mode: forwards;
     -webkit-transform-origin: 0 0;
+    transform-origin: 0 0;
 
     // so that border won't show when height is 0.
     box-sizing: border-box;

src/styles/brackets_patterns_override.less

@@ -239,6 +239,10 @@ a:focus {
     0%   { opacity: 0.5; -webkit-transform: translate3d(0, 0, 0) scale(0.5); }
     100% { opacity: 1; -webkit-transform: translate3d(0, 0, 0) scale(1); }
 }
+@keyframes dropdown {
+    0%   { opacity: 0.5; transform: translate3d(0, 0, 0) scale(0.5); }
+    100% { opacity: 1; transform: translate3d(0, 0, 0) scale(1); }
+}
 
 // Code hints don't need scaling navigation so we're removing it
 
@@ -615,11 +619,19 @@ a:focus {
     0%   { opacity: 0; -webkit-transform: translate3d(0, 0, 0); }
     100% { opacity: 0.4; -webkit-transform: translate3d(0, 0, 0); }
 }
+@keyframes backdrop {
+    0%   { opacity: 0; transform: translate3d(0, 0, 0); }
+    100% { opacity: 0.4; transform: translate3d(0, 0, 0); }
+}
 
 @-webkit-keyframes modal {
     0%   { opacity: 0; -webkit-transform: translate3d(0, 0, 0) scale(0); }
     100% { opacity: 1; -webkit-transform: translate3d(0, 0, 0) scale(1); }
 }
+@keyframes modal {
+    0%   { opacity: 0; transform: translate3d(0, 0, 0) scale(0); }
+    100% { opacity: 1; transform: translate3d(0, 0, 0) scale(1); }
+}
 
 
 .dialog-title {