Added clearColor, clearDepth and clearStencil placeholder methods to CanvasRenderer.

src/renderers/CanvasRenderer.js

@@ -248,9 +248,14 @@ THREE.CanvasRenderer = function ( parameters ) {
 
 		}
 
-
 	};
 
+	// compatibility
+
+	this.clearColor = function () {};
+	this.clearDepth = function () {};
+	this.clearStencil = function () {};
+
 	this.render = function ( scene, camera ) {
 
 		if ( camera instanceof THREE.Camera === false ) {