LayoutTests/webgl/webgl-extension-directive-location-no-error.html - WebKit - Git at Google

 <body>
 <p>Ensure that if a shader extension directive is specified after non-preprocessor symbols, no errors are logged.</p>
 <canvas></canvas>
 <script>
 if (window.testRunner)
     testRunner.dumpAsText();

 const fragmentShaderSource = `
     precision highp float;
     #extension GL_OES_standard_derivatives : enable

     void main() {
         gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
     }
     `;

 const canvas = document.querySelector('canvas');
 const gl = canvas.getContext("webgl");

 gl.getExtension('OES_standard_derivatives');

 const shader = gl.createShader(gl.FRAGMENT_SHADER);
 gl.shaderSource(shader, fragmentShaderSource);
 gl.compileShader(shader);
 const success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
 if (!success)
     console.log(gl.getShaderInfoLog(shader));
 </script>
 </body>
	<body>
	<p>Ensure that if a shader extension directive is specified after non-preprocessor symbols, no errors are logged.</p>
	<canvas></canvas>
	<script>
	if (window.testRunner)
	testRunner.dumpAsText();

	const fragmentShaderSource = `
	precision highp float;
	#extension GL_OES_standard_derivatives : enable

	void main() {
	gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
	}
	`;

	const canvas = document.querySelector('canvas');
	const gl = canvas.getContext("webgl");

	gl.getExtension('OES_standard_derivatives');

	const shader = gl.createShader(gl.FRAGMENT_SHADER);
	gl.shaderSource(shader, fragmentShaderSource);
	gl.compileShader(shader);
	const success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
	if (!success)
	console.log(gl.getShaderInfoLog(shader));
	</script>
	</body>