Add some layout tests about behavior on undefined and null.

LayoutTests/fast/canvas/canvas-pattern-behaviour.js

 description("This test covers the behaviour of pattern use and construction");
 
 function dataToArray(data) {
     var result = new Array(data.length)
     for (var i = 0; i < data.length; i++)
         result[i] = data[i];
     return result;
 }
 
 function getPixel(x, y) {
@@ skipping 50 matching lines @@
     function () {
         shouldThrow("context.createPattern(green1x1, undefined)");
     },
     function () {
         shouldThrow("context.createPattern(green1x1, 'undefined')");
     },
     function () {
         shouldThrow("context.createPattern(green1x1, {toString:function(){ return null;}})");
     },
     function () {
+        shouldThrow("context.createPattern(null, '')");
+    },
+    function () {
+        shouldThrow("context.createPattern(undefined, '')");
+    },
+    function () {
+        shouldThrow("context.createPattern({}, '')");
+    },
+    function () {
+        shouldThrow("context.createPattern([], '')");
+    },
+    function () {
         var didThrow = false;
         try {
             var pattern = context.createPattern(green1x1, '');
         } catch (e) {
             didThrow = true;
             testFailed("context.createPattern(green1x1, '') threw exception "+e)
         }
         if (!didThrow)
             testPassed("context.createPattern(green1x1, '') did not throw an exception");
 
@@ skipping 33 matching lines @@
         pixelShouldBe(98,  1, [0,128,0,255]);
         pixelShouldBe(1,  48, [0,128,0,255]);
         pixelShouldBe(98, 48, [0,128,0,255]);
     },
 ];
 for (var i = 0; i < tests.length; i++) {
     context.fillStyle="red";
     context.fillRect(0,0,100,50);
     tests[i]();
 }