fix(autocomplete example): regex metacharacter escape (#4921)

* fix(autocopmplete): regex metacharacter escape

autocomplete material example fails if regex metacharacter (ie *) is provided. Fixed by adding escapeSpecChars function

* Update autocomplete-overview-example.ts

* fix(autocopmplete): regex replaced with includes

* Extra newline removed

* Update autocomplete-overview-example.ts

src/material-examples/autocomplete-overview/autocomplete-overview-example.ts

@@ -73,7 +73,7 @@ export class AutocompleteOverviewExample {
   }
 
   filterStates(val: string) {
-    return val ? this.states.filter(s => new RegExp(`^${val}`, 'gi').test(s))
+    return val ? this.states.filter(s => s.toLowerCase().indexOf(val.toLowerCase()) === 0)
                : this.states;
   }