Pull async matchers out to their own functions

- Makes AsyncExpectation closer to Expectation

src/core/matchers/async/toBeResolved.js

@@ -0,0 +1,22 @@
+getJasmineRequireObj().toBeResolved = function(j$) {
+  /**
+   * Expect a promise to be resolved.
+   * @function
+   * @async
+   * @name async-matchers#toBeResolved
+   * @example
+   * await expectAsync(aPromise).toBeResolved();
+   * @example
+   * return expectAsync(aPromise).toBeResolved();
+   */
+  return function toBeResolved(util) {
+    return {
+      compare: function(actual) {
+        return actual.then(
+          function() { return {pass: true}; },
+          function() { return {pass: false}; }
+        );
+      }
+    };
+  };
+};