WebGLRenderer: Added getContextAttributes for awareness reasons. See #6899.

src/renderers/WebGLRenderer.js

@@ -381,6 +381,12 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 	};
 
+	this.getContextAttributes = function () {
+
+		return _gl.getContextAttributes();
+
+	};
+
 	this.forceContextLoss = function () {
 
 		extensions.get( 'WEBGL_lose_context' ).loseContext();