WebGLRenderer: Clean up.

src/renderers/WebGLRenderer.js

@@ -2665,18 +2665,19 @@ function WebGLRenderer( parameters ) {
 			try {
 
 				var texture = renderTarget.texture;
+				var textureFormat = texture.format;
+				var textureType = texture.type;
 
-				if ( texture.format !== RGBAFormat && paramThreeToGL( texture.format ) !== _gl.getParameter( _gl.IMPLEMENTATION_COLOR_READ_FORMAT ) ) {
+				if ( textureFormat !== RGBAFormat && paramThreeToGL( textureFormat ) !== _gl.getParameter( _gl.IMPLEMENTATION_COLOR_READ_FORMAT ) ) {
 
 					console.error( 'THREE.WebGLRenderer.readRenderTargetPixels: renderTarget is not in RGBA or implementation defined format.' );
 					return;
 
 				}
 
-				if ( texture.type !== UnsignedByteType &&
-				     paramThreeToGL( texture.type ) !== _gl.getParameter( _gl.IMPLEMENTATION_COLOR_READ_TYPE ) &&
-				     ! ( texture.type === FloatType && ( extensions.get( 'OES_texture_float' ) || extensions.get('WEBGL_color_buffer_float') ) ) &&
-				     ! ( texture.type === HalfFloatType && extensions.get( 'EXT_color_buffer_half_float' ) ) ) {
+				if ( textureType !== UnsignedByteType && paramThreeToGL( textureType ) !== _gl.getParameter( _gl.IMPLEMENTATION_COLOR_READ_TYPE ) && // IE11, Edge and Chrome Mac < 52 (#9513)
+				     ! ( textureType === FloatType && ( extensions.get( 'OES_texture_float' ) || extensions.get( 'WEBGL_color_buffer_float' ) ) ) && // Chrome Mac >= 52 and Firefox
+				     ! ( textureType === HalfFloatType && extensions.get( 'EXT_color_buffer_half_float' ) ) ) {
 
 					console.error( 'THREE.WebGLRenderer.readRenderTargetPixels: renderTarget is not in UnsignedByteType or implementation defined type.' );
 					return;
@@ -2689,7 +2690,7 @@ function WebGLRenderer( parameters ) {
 
 					if ( ( x >= 0 && x <= ( renderTarget.width - width ) ) && ( y >= 0 && y <= ( renderTarget.height - height ) ) ) {
 
-						_gl.readPixels( x, y, width, height, paramThreeToGL( texture.format ), paramThreeToGL( texture.type ), buffer );
+						_gl.readPixels( x, y, width, height, paramThreeToGL( textureFormat ), paramThreeToGL( textureType ), buffer );
 
 					}