backport - Bug 1448523 - Disable browser_dbg-babel-preview.js on windows10-64-ccov. r=jmaher

Author: jasonLaster

src/test/mochitest/browser.ini

@@ -138,6 +138,7 @@ support-files =
 [browser_dbg-babel-scopes.js]
 [browser_dbg-babel-stepping.js]
 [browser_dbg-babel-preview.js]
+skip-if = (os == "win" && ccov) # Bug 1448523
 [browser_dbg-breaking.js]
 [browser_dbg-breaking-from-console.js]
 [browser_dbg-breakpoints.js]