relayout: add support for calls with null for annotation / shape

- to be part with other array containers

Author: etpinard

src/plot_api/plot_api.js

@@ -1921,6 +1921,9 @@ function _relayout(gd, aobj) {
                 objList = layout[objType] || [],
                 obji = objList[objNum] || {};
 
+            // new API, remove annotation / shape with `null`
+            if(vi === null) aobj[ai] = 'remove';
+
             // if p.parts is just an annotation number, and val is either
             // 'add' or an entire annotation to add, the undo is 'remove'
             // if val is 'remove' then undo is the whole annotation object

test/jasmine/tests/annotations_test.js

@@ -69,11 +69,18 @@ describe('annotations relayout', function() {
             expect(countAnnotations()).toEqual(len + 1);
 
             return Plotly.relayout(gd, 'annotations[' + 0 + ']', 'remove');
-        }).then(function() {
+        })
+        .then(function() {
             expect(countAnnotations()).toEqual(len);
 
+            return Plotly.relayout(gd, 'annotations[' + 0 + ']', null);
+        })
+        .then(function() {
+            expect(countAnnotations()).toEqual(len - 1);
+
             return Plotly.relayout(gd, { annotations: [] });
-        }).then(function() {
+        })
+        .then(function() {
             expect(countAnnotations()).toEqual(0);
 
             done();

test/jasmine/tests/shapes_test.js

@@ -183,12 +183,21 @@ describe('Test shapes:', function() {
                 expect(countShapePathsInUpperLayer()).toEqual(pathCount + 1);
                 expect(getLastShape(gd)).toEqual(shape);
                 expect(countShapes(gd)).toEqual(index + 1);
-            }).then(function() {
-                Plotly.relayout(gd, 'shapes[' + index + ']', 'remove');
-            }).then(function() {
+            })
+            .then(function() {
+                return Plotly.relayout(gd, 'shapes[' + index + ']', 'remove');
+            })
+            .then(function() {
                 expect(countShapePathsInUpperLayer()).toEqual(pathCount);
                 expect(countShapes(gd)).toEqual(index);
-            }).then(done);
+
+                return Plotly.relayout(gd, 'shapes[' + 1 + ']', null);
+            })
+            .then(function() {
+                expect(countShapePathsInUpperLayer()).toEqual(pathCount - 1);
+                expect(countShapes(gd)).toEqual(index - 1);
+            })
+            .then(done);
         });
 
         it('should be able to remove all shapes', function(done) {