Relax createImageBitmap parameter check

Allow null or undefined in place of the "options" parameter.

Change-Id: I69048e7366781fc7842976c53f717c3d5f5b2bf8

src/tabris/ImageBitmap.js

@@ -118,14 +118,14 @@ function getOptions(args) {
     throw new TypeError(`${args.length} is not a valid argument count for any overload of createImageBitmap.`);
   }
   const options = {};
-  if (args.length === 2) {
+  if (args.length === 2 && args[1] != null) {
     if (!(args[1] instanceof Object)) {
       throw new TypeError('Argument 2 of createImageBitmap is not an object.');
     }
     Object.assign(options, args[1]);
   } else if (args.length >= 5) {
     if (args.length === 6) {
-      if (!(args[5] instanceof Object)) {
+      if (args[5] != null && !(args[5] instanceof Object)) {
         throw new TypeError('Argument 6 of createImageBitmap is not an object.');
       }
     }

test/tabris/ImageBitmap.test.js

@@ -398,6 +398,13 @@ describe('ImageBitmap', function() {
       });
     });
 
+    it('ignores null', function() {
+      createImageBitmap(new Blob(), null);
+
+      const call = client.calls({type: 'tabris.ImageBitmap', op: 'create'})[0];
+      expect(call.properties).to.deep.equal({});
+    });
+
   });
 
   describe('with source rectangle', function() {
@@ -412,6 +419,15 @@ describe('ImageBitmap', function() {
       expect(call.properties).to.deep.equal(Object.assign({}, options, {rect}));
     });
 
+    it('ignores null for options', function() {
+      const rect = {sx: 0, sy: 1, sw: 2, sh: 3};
+
+      createImageBitmap(new Blob(), rect.sx, rect.sy, rect.sw, rect.sh, null);
+
+      const call = client.calls({type: 'tabris.ImageBitmap', op: 'create'})[0];
+      expect(call.properties).to.deep.equal(Object.assign({}, {rect}));
+    });
+
     it('normalizes rect', function() {
       createImageBitmap(new Blob(), 0.1, 1, '2', 3);