Fixing API; addressing @mpriour's doc comment

Previously, minFrameRate could not be set as option with the start method.
The tests failed to catch this flaw. Now both the start method and the
tests are fixed.

tests/Tween.html

@@ -79,29 +79,32 @@
         t.plan(2);
         
         var tween = new OpenLayers.Tween();
-        var log1 = 0;
+        var log = 0;
         tween.start({count: 0}, {count: 10}, 10, {
             callbacks: {
                 eachStep: function() {
-                    log1++;
+                    log++;
                 }
             },
             minFrameRate: 10000
         });
         
-        var log2 = 0;
-        tween.start({count: 0}, {count: 10}, 10, {
-            callbacks: {
-                eachStep: function() {
-                    log2++;
-                }
-            },
-            minFrameRate: 1
-        });
-
         t.delay_call(0.8, function() {
-            t.eq(log1, 0, 'all frames skipped at a frame rate of 10000');            
-            t.eq(log2, 11, 'no frames skipped at a frame rate of 1');            
+            t.eq(log, 0, 'all frames skipped at a frame rate of 10000');
+            
+            log = 0;
+            tween.start({count: 0}, {count: 10}, 10, {
+                callbacks: {
+                    eachStep: function() {
+                        log++;
+                    }
+                },
+                minFrameRate: 1
+            });
+        });
+        
+        t.delay_call(1.6, function() {
+            t.eq(log, 11, 'no frames skipped at a frame rate of 1');            
         });
     }