Refactor suite timing out of Env and into each Reporter

[finishes #45659879]

src/core/Timer.js

@@ -0,0 +1,18 @@
+getJasmineRequireObj().Timer = function() {
+  function Timer(options) {
+    options = options || {};
+
+    var now = options.now || function() { return new Date().getTime(); },
+        startTime;
+
+    this.start = function() {
+      startTime = now();
+    };
+
+    this.elapsed = function() {
+      return now() - startTime;
+    };
+  }
+
+  return Timer;
+};