Removing getPolicyNames. (#264)

A proper introspection at policy creation time (possibly via events)
will be created at a later point.

Fixes #235.

dist/cjs/trustedtypes.api_only.js

@@ -529,18 +529,6 @@ const trustedTypesBuilderTestOnly = function() {
     return deepClone(map);
   }
 
-  /**
-   * Returns all configured policy names (even for non-exposed policies).
-   * @return {!Array<string>}
-   */
-  function getPolicyNames() {
-    // TODO(msamuel): Should we sort policyNames to avoid leaking or
-    // encouraging dependency on the order in which policy names are
-    // registered?  I think JavaScript builtin sorts are efficient for
-    // almost-sorted lists so the amortized cost is close to O(n).
-    return policyNames.slice();
-  }
-
   /**
    * Creates a TT policy.
    *
@@ -630,8 +618,6 @@ const trustedTypesBuilderTestOnly = function() {
     // The main function to create policies.
     createPolicy,
 
-    getPolicyNames,
-
     // Type checkers, also validating the object was initialized through a
     // policy.
     isHTML: isTrustedTypeChecker(TrustedHTML),
@@ -711,7 +697,6 @@ function setupPolyfill() {
     'isScriptURL': tt.isScriptURL,
     'isScript': tt.isScript,
     'createPolicy': tt.createPolicy,
-    'getPolicyNames': tt.getPolicyNames,
     'getAttributeType': tt.getAttributeType,
     'getPropertyType': tt.getPropertyType,
     'getTypeMapping': tt.getTypeMapping,