fix(@angular/build): ensure matching coverage excludes with karma on Windows

When on Windows, the coverage exclusion paths need to be made
absolute via the Node.js path builtin to ensure matching
with the files during the build process.

Author: clydin

packages/angular/build/src/builders/karma/application_builder.ts

@@ -614,7 +614,7 @@ function getInstrumentationExcludedPaths(root: string, excludedPaths: string[]):
 
   for (const excludeGlob of excludedPaths) {
     const excludePath = excludeGlob[0] === '/' ? excludeGlob.slice(1) : excludeGlob;
-    globSync(excludePath, { absolute: true, cwd: root }).forEach((p) => excluded.add(p));
+    globSync(excludePath, { cwd: root }).forEach((p) => excluded.add(path.join(root, p)));
   }
 
   return excluded;