[Fixed Position] Initially implement handles

Initially implement handles for resizing elements in a fixed
position view, WTD-882.

platform/features/layout/test/FixedDragHandleSpec.js

@@ -0,0 +1,62 @@
+/*global define,describe,it,expect,beforeEach,jasmine,xit*/
+
+define(
+    ['../src/FixedDragHandle'],
+    function (FixedDragHandle) {
+        "use strict";
+
+        var TEST_GRID_SIZE = [ 13, 33 ];
+
+        describe("A fixed position drag handle", function () {
+            var mockElementHandle,
+                mockCommit,
+                handle;
+
+            beforeEach(function () {
+                mockElementHandle = jasmine.createSpyObj(
+                    'elementHandle',
+                    [ 'x', 'y' ]
+                );
+                mockCommit = jasmine.createSpy('commit');
+
+                mockElementHandle.x.andReturn(6);
+                mockElementHandle.y.andReturn(8);
+
+                handle = new FixedDragHandle(
+                    mockElementHandle,
+                    TEST_GRID_SIZE,
+                    mockCommit
+                );
+            });
+
+            it("provides a style for positioning", function () {
+                var style = handle.style();
+                // 6 grid coords * 13 pixels - 4 pixels for centering
+                expect(style.left).toEqual('74px');
+                // 8 grid coords * 33 pixels - 4 pixels for centering
+                expect(style.top).toEqual('260px');
+            });
+
+            it("allows handles to be dragged", function () {
+                handle.startDrag();
+                handle.continueDrag([ 16, 8 ]);
+
+                // Should update x/y, snapped to grid
+                expect(mockElementHandle.x).toHaveBeenCalledWith(7);
+                expect(mockElementHandle.y).toHaveBeenCalledWith(8);
+
+                handle.continueDrag([ -16, -35 ]);
+
+                // Should have interpreted relative to initial state
+                expect(mockElementHandle.x).toHaveBeenCalledWith(5);
+                expect(mockElementHandle.y).toHaveBeenCalledWith(7);
+
+                // Finally, ending drag should commit
+                expect(mockCommit).not.toHaveBeenCalled();
+                handle.endDrag();
+                expect(mockCommit).toHaveBeenCalled();
+            });
+
+        });
+    }
+);