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diff --git a/dom/canvas/test/webgl-conf/checkout/conformance/reading/fbo-remains-unchanged-after-read-pixels.html b/dom/canvas/test/webgl-conf/checkout/conformance/reading/fbo-remains-unchanged-after-read-pixels.html
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index 0000000000..00e8dcd9a0
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+++ b/dom/canvas/test/webgl-conf/checkout/conformance/reading/fbo-remains-unchanged-after-read-pixels.html
@@ -0,0 +1,105 @@
+<!--
+Copyright (c) 2019 The Khronos Group Inc.
+Use of this source code is governed by an MIT-style license that can be
+found in the LICENSE.txt file.
+-->
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<link rel="stylesheet" href="../../resources/js-test-style.css"/>
+<script src="../../js/js-test-pre.js"></script>
+<script src="../../js/webgl-test-utils.js"></script>
+</head>
+<body>
+<div id="description"></div>
+<div id="console"></div>
+<canvas id="canvas" width="4" height="4"></canvas>
+<script id="vshader" type="x-shader/x-vertex">
+attribute vec3 a_pos;
+attribute vec4 a_color;
+varying vec4 v_color;
+
+void main()
+{
+    v_color = a_color;
+    gl_Position = vec4(a_pos.xyz, 1.0);
+}
+</script>
+
+<script id="fshader" type="x-shader/x-fragment">
+precision mediump float;
+
+varying vec4 v_color;
+
+void main()
+{
+    gl_FragColor = v_color;
+}
+</script>
+
+<script>
+"use strict";
+
+description("when antialias is enabled, verify default fbo pixels would not be changed between two readPixels without drawing operations");
+var wtu = WebGLTestUtils;
+var N = 4;
+
+var vertices = new Float32Array([
+         1.0, 1.0, 0.0,
+        -1.0, -1.0, 0.0]);
+var colors = new Uint8Array([
+        255, 0, 0, 255,
+        255, 0, 0, 255]);
+
+var canvas = document.getElementById('canvas');
+var gl = wtu.create3DContext(canvas, {antialias: true});
+
+if (!gl) {
+  testFailed("context does not exist");
+} else {
+  testPassed("context exists");
+
+  var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["a_pos", "a_color"]);
+  gl.clearColor(0, 0, 0, 1);
+  gl.clear(gl.COLOR_BUFFER_BIT);
+
+  var colorOffset = vertices.byteLength;
+  var vbo = gl.createBuffer();
+  gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
+  gl.bufferData(gl.ARRAY_BUFFER, colorOffset + colors.byteLength, gl.STATIC_DRAW);
+  gl.bufferSubData(gl.ARRAY_BUFFER, 0, vertices);
+  gl.bufferSubData(gl.ARRAY_BUFFER, colorOffset, colors);
+
+  gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0);
+  gl.enableVertexAttribArray(0);
+  gl.vertexAttribPointer(1, 4, gl.UNSIGNED_BYTE, true, 0, colorOffset);
+  gl.enableVertexAttribArray(1);
+  gl.drawArrays(gl.LINES, 0, vertices.length / 3);
+
+  var result_1 = new Uint8Array(N * N * 4);
+  var result_2 = new Uint8Array(N * N * 4);
+  gl.readPixels(0, 0, N, N, gl.RGBA, gl.UNSIGNED_BYTE, result_1);
+  gl.readPixels(0, 0, N, N, gl.RGBA, gl.UNSIGNED_BYTE, result_2);
+  wtu.glErrorShouldBe(gl, gl.NO_ERROR);
+
+  var tolerance = 0;
+  var diff = new Uint8Array(N * N * 4);
+  var failed = wtu.comparePixels(result_1, result_2, tolerance, diff);
+
+  if (failed) {
+    testFailed("default fbo pixels had be changed between two readPixels without drawing operations");
+  } else {
+    testPassed("default fbo pixels had not be changed between two readPixels without drawing operations.");
+  }
+
+  gl.bindBuffer(gl.ARRAY_BUFFER, null);
+  gl.deleteBuffer(vbo);
+}
+
+var successfullyParsed = true;
+</script>
+<script src="../../js/js-test-post.js"></script>
+</body>
+</html>