Revert "Add OES_standard_derivatives if available"

This reverts commit 21ef5de.

Author: MAJigsaw77

src/openfl/display/OpenGLRenderer.hx

@@ -55,7 +55,6 @@ import lime.math.Matrix4;
 class OpenGLRenderer extends DisplayObjectRenderer
 {
 	@:noCompletion private static var __blendMinMaxSupported:Null<Bool>;
-	@:noCompletion private static var __standardDerivativesSupported:Null<Bool>;
 	@:noCompletion private static var __complexBlendsSupported:Null<Bool>;
 	@:noCompletion private static var __coherentBlendsSupported:Null<Bool>;
 	@:noCompletion private static var __sRGBWriteControlSupported:Null<Bool>;
@@ -173,10 +172,6 @@ class OpenGLRenderer extends DisplayObjectRenderer
 		{
 			__coherentBlendsSupported = exts.contains("KHR_blend_equation_advanced_coherent");
 		}
-		if (__standardDerivativesSupported == null)
-		{
-			__standardDerivativesSupported = exts.contains("OES_standard_derivatives");
-		}
 
 		#if (js && html5)
 		__softwareRenderer = new CanvasRenderer(null);

src/openfl/display/Shader.hx

@@ -627,7 +627,6 @@ class Shader
 		}
 
 		var complexBlendsSupported = OpenGLRenderer.__complexBlendsSupported && isFragment;
-		var standardDerivativesSupported = OpenGLRenderer.__standardDerivativesSupported && isFragment;
 
 		#if lime
 		if (__context.__context.type == OPENGL)
@@ -654,11 +653,6 @@ class Shader
 			#end
 		}
 
-		if (standardDerivativesSupported)
-		{
-			extensions += "#extension GL_OES_standard_derivatives : enable\n";
-		}
-
 		// #version must be the first directive and cannot be repeated,
 		// while #extension directives must be before any non-preprocessor tokens.