Use explicit case-insensitive attribute-value matching in UA-stylesheets

Source/core/css/mediaControls.css

Index: Source/core/css/mediaControls.css
diff --git a/Source/core/css/mediaControls.css b/Source/core/css/mediaControls.css
index d3b5536e4a4526b8ceab2ba14b949ae3bbfd4843..19acd2d889b8bd95d456e142aa53328e8b5c61a7 100644
--- a/Source/core/css/mediaControls.css
+++ b/Source/core/css/mediaControls.css
@@ -239,7 +239,7 @@ audio::-webkit-media-controls-volume-slider, video::-webkit-media-controls-volum
    https://code.google.com/p/chromium/issues/detail?id=112508
    https://bugs.webkit.org/show_bug.cgi?id=62218
 */
-input[type="range"]::-webkit-media-slider-container {
+input[type="range" i]::-webkit-media-slider-container {
     display: flex;
     align-items: center;
     flex-direction: row; /* This property is updated by C++ code. */
@@ -252,11 +252,11 @@ input[type="range"]::-webkit-media-slider-container {
 }
 
 /* The negative right margin causes the track to overflow its container. */
-input[type="range"]::-webkit-media-slider-container > div {
+input[type="range" i]::-webkit-media-slider-container > div {
     margin-right: -14px;
 }
 
-input[type="range"]::-webkit-media-slider-thumb {
+input[type="range" i]::-webkit-media-slider-thumb {
     margin-left: -7px;
     margin-right: -7px;
 }