Ignore EXT_frag_depth for WebGL 2.0

src/renderers/webgl/WebGLExtensions.js

@@ -60,7 +60,8 @@ function WebGLExtensions( gl ) {
 						  'OES_texture_half_float',
 						  'OES_texture_half_float_linear',
 						  'OES_element_index_uint',
-						  'OES_standard_derivatives' ].indexOf( name ) >= 0 ) {
+						  'OES_standard_derivatives',
+						  'EXT_frag_depth' ].indexOf( name ) >= 0 ) {
 
 						extension = gl;
 

src/renderers/webgl/WebGLProgram.js

@@ -85,7 +85,7 @@ function generateExtensions( extensions, parameters, rendererExtensions, isWebGL
 
 	var chunks = [
 		( ! isWebGL2 && ( extensions.derivatives || parameters.envMapCubeUV || parameters.bumpMap || parameters.normalMap || parameters.flatShading ) ) ? '#extension GL_OES_standard_derivatives : enable' : '',
-		( extensions.fragDepth || parameters.logarithmicDepthBuffer ) && rendererExtensions.get( 'EXT_frag_depth' ) ? '#extension GL_EXT_frag_depth : enable' : '',
+		( ! isWebGL2 && ( extensions.fragDepth || parameters.logarithmicDepthBuffer ) && rendererExtensions.get( 'EXT_frag_depth' ) ) ? '#extension GL_EXT_frag_depth : enable' : '',
 		( extensions.drawBuffers ) && rendererExtensions.get( 'WEBGL_draw_buffers' ) ? '#extension GL_EXT_draw_buffers : require' : '',
 		( ! isWebGL2 && ( extensions.shaderTextureLOD || parameters.envMap ) && rendererExtensions.get( 'EXT_shader_texture_lod' ) ) ? '#extension GL_EXT_shader_texture_lod : enable' : ''
 	];
@@ -532,6 +532,7 @@ function WebGLProgram( renderer, extensions, code, material, shader, parameters
 			'#define varying in',
 			'out highp vec4 pc_fragColor;',
 			'#define gl_FragColor pc_fragColor',
+			'#define gl_FragDepthEXT gl_FragDepth',
 			'#define texture2D texture',
 			'#define textureCube texture',
 			'#define texture2DProj textureProj',