add gutter option

test/rendering/cases/webgl-data-tile-interpolate-gutter/main.js

@@ -0,0 +1,33 @@
+import DataTile from '../../../../src/ol/source/DataTile.js';
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/WebGLTile.js';
+import View from '../../../../src/ol/View.js';
+
+const size = 260;
+
+const data = new Uint8Array(size * size);
+for (let row = 0; row < size; ++row) {
+  for (let col = 0; col < size; ++col) {
+    data[row * size + col] = (row + col) % 2 === 0 ? 255 : 0;
+  }
+}
+
+new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: new DataTile({
+        maxZoom: 1,
+        interpolate: true,
+        loader: () => data,
+        gutter: 2,
+      }),
+    }),
+  ],
+  view: new View({
+    center: [0, 0],
+    zoom: 5,
+  }),
+});
+
+render();