fix(theming): match preceding selectors as well

* The theming service currently only matches from the beginning of the `md-default-theme`, but all preceding selectors are being ignored.

Fixes #9480

Author: devversion

src/core/services/theming/theming.js

@@ -744,7 +744,7 @@ function parseRules(theme, colorType, rules) {
     // Don't apply a selector rule to the default theme, making it easier to override
     // styles of the base-component
     if (theme.name == 'default') {
-      var themeRuleRegex = /((?:(?:(?: |>|\.|\w|-|:|\(|\)|\[|\]|"|'|=)+) )?)((?:(?:\w|\.|-)+)?)\.md-default-theme((?: |>|\.|\w|-|:|\(|\)|\[|\]|"|'|=)*)/g;
+      var themeRuleRegex = /((?: |>|\.|\w|-|:|\(|\)|\[|\]|"|'|=)*)((?:(?:\w|\.|-)+)?)\.md-default-theme((?: |>|\.|\w|-|:|\(|\)|\[|\]|"|'|=)*)/g;
       newRule = newRule.replace(themeRuleRegex, function(match, prefix, target, suffix) {
         return match + ', ' + prefix + target + suffix;
       });