Fix webgl packaging

addons/xterm-addon-webgl/src/WebglAddon.ts

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2017 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { Terminal, ITerminalAddon } from 'xterm';
+import { WebglRenderer } from './WebglRenderer';
+import { IRenderService } from 'browser/services/Services';
+import { IColorSet } from 'browser/Types';
+
+export class WebglAddon implements ITerminalAddon {
+  constructor(
+    private _preserveDrawingBuffer?: boolean
+  ) {}
+
+  public activate(terminal: Terminal): void {
+    if (!terminal.element) {
+      throw new Error('Cannot activate WebglRendererAddon before Terminal.open');
+    }
+    const renderService: IRenderService =  (<any>terminal)._core._renderService;
+    const colors: IColorSet = (<any>terminal)._core._colorManager.colors;
+    renderService.setRenderer(new WebglRenderer(terminal, colors, this._preserveDrawingBuffer));
+  }
+
+  public dispose(): void {
+    throw new Error('WebglRendererAddon.dispose Not yet implemented');
+  }
+}