Revert of gpu: Expose internal format R8 instead of RED.

gpu/GLES2/extensions/CHROMIUM/CHROMIUM_image.txt

 Name
 
     CHROMIUM_image
 
 Name Strings
 
     GL_CHROMIUM_image
 
 Version
 
@@ skipping 28 matching lines @@
 
     Create an image from <buffer> with width equal to <width> and
     height equal to <height> and format equal to <internalformat>.
 
     Returns a unique identifier for the image that could be used in
     subsequent operations.
 
     INVALID_VALUE is generated if <width> or <height> is nonpositive.
 
     INVALID_VALUE is generated if <internalformat> is not one of
-    R8, RGB, RGBA, BGRA_EXT, ATC_RGB_AMD, ATC_RGBA_INTERPOLATED_ALPHA_AMD,
+    RED, RGB, RGBA, BGRA_EXT, ATC_RGB_AMD, ATC_RGBA_INTERPOLATED_ALPHA_AMD,
     COMPRESSED_RGB_S3TC_DXT1_EXT, COMPRESSED_RGBA_S3TC_DXT5_EXT or
     ETC1_RGB8_OES.
 
     void DestroyImageCHROMIUM(GLuint image_id)
 
     Frees the image previously created by a call to CreateImageCHROMIUM.
 
     INVALID_OPERATION is generated if <image_id> is not a valid image id.
 
 Dependencies on EXT_texture_format_BGRA8888
 
     If EXT_texture_format_BGRA8888 is not supported:
      * delete any reference to the BGRA_EXT format.
 
 Dependencies on ARB_texture_rg
 
     If ARB_texture_rg is not supported:
-     * delete any reference to the R8 format.
+     * delete any reference to the RED format.
 
 Dependencies on AMD_compressed_ATC_texture
 
     If AMD_compressed_ATC_texture is not supported:
      * delete any reference to the ATC_RGB_AMD and
        ATC_RGBA_INTERPOLATED_ALPHA_AMD formats.
 
 Dependencies on EXT_texture_compression_s3tc
 
     If EXT_texture_compression_s3tc is not supported:
@@ skipping 15 matching lines @@
 
 Revision History
 
     5/9/2013    Documented the extension
     4/30/2014   Moved usage flag to creation function.
     10/7/2014   Remove map/unmap API.
     4/6/2015    Add BGRA_EXT format.
     2/7/2015    Add R8 format.
     5/13/2015   Add compressed formats.
     11/5/2015   Change R8 format to RED.
-    2/18/2016   Change back RED internal format to R8.