When unable to create GL context, throw meaningful error rather than later...

When unable to create GL context, throw meaningful error rather than later failing in extensions.get()

src/renderers/WebGLRenderer.js

@@ -232,7 +232,7 @@ function WebGLRenderer( parameters ) {
 	} catch ( error ) {
 
 		console.error( 'THREE.WebGLRenderer: ' + error.message );
-
+		throw error;
 	}
 
 	var extensions, capabilities, state, info;