Css: Revert 24e587929f

The workaround to be able to change !important styles broke the browser
keeping the old CSS value if the new one was rejected. Patching it would
involve a significant perf hit (~33%) so the initial patch needs to be
reverted instead.

Tests by m_gol & gibson042.

(cherry-picked from 10e654218a)

Fixes #14836
Closes gh-1532

src/css.js

@@ -295,9 +295,6 @@ jQuery.extend({
 				// Support: IE
 				// Swallow errors from 'invalid' CSS values (#5509)
 				try {
-					// Support: Chrome, Safari
-					// Setting style to blank string required to delete "style: x !important;"
-					style[ name ] = "";
 					style[ name ] = value;
 				} catch(e) {}
 			}