WebGLProgram: Clean up.

src/renderers/webgl/WebGLProgram.js

@@ -795,11 +795,11 @@ function WebGLProgram( renderer, cacheKey, parameters ) {
 
 	}
 
-	// clean up
+	// Clean up
 
-	// spec fails on iOS 10 or lower - #18402
-	//gl.detachShader( program, glVertexShader );
-	//gl.detachShader( program, glFragmentShader );
+	// Crashes in iOS9 and iOS10. #18402
+	// gl.detachShader( program, glVertexShader );
+	// gl.detachShader( program, glFragmentShader );
 
 	gl.deleteShader( glVertexShader );
 	gl.deleteShader( glFragmentShader );