Try to not use MAGNUM_TARGET_GLES3.

It's confusing and should be removed (what if we have ES4?).

src/Magnum/AbstractTexture.cpp

@@ -548,7 +548,7 @@ ColorFormat AbstractTexture::imageFormatForInternalFormat(const TextureFormat in
         case TextureFormat::RGB5:
         #endif
         case TextureFormat::RGB565:
-        #if !defined(MAGNUM_TARGET_GLES3) && !defined(MAGNUM_TARGET_WEBGL)
+        #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_GLES2) && !defined(MAGNUM_TARGET_WEBGL))
         case TextureFormat::RGB10:
         #endif
         #ifndef MAGNUM_TARGET_GLES
@@ -806,7 +806,7 @@ ColorType AbstractTexture::imageTypeForInternalFormat(const TextureFormat intern
             return ColorType::UnsignedShort565;
 
         #if !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
-        #ifndef MAGNUM_TARGET_GLES3
+        #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
         case TextureFormat::RGB10:
         #endif
         case TextureFormat::RGB10A2:

src/Magnum/Test/MeshGLTest.cpp

@@ -349,7 +349,7 @@ FloatShader::FloatShader(const std::string& type, const std::string& conversion)
     #endif
 
     vert.addSource(
-        #ifndef MAGNUM_TARGET_GLES3
+        #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
         "attribute mediump " + type + " value;\n"
         "varying mediump " + type + " valueInterpolated;\n"
         #else
@@ -361,7 +361,7 @@ FloatShader::FloatShader(const std::string& type, const std::string& conversion)
         "    gl_Position = vec4(0.0, 0.0, 0.0, 1.0);\n"
         "}\n");
 
-    #ifndef MAGNUM_TARGET_GLES3
+    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
     frag.addSource("varying mediump " + type + " valueInterpolated;\n"
                    "void main() { gl_FragColor = " + conversion + "; }\n");
     #else

src/Magnum/Text/DistanceFieldGlyphCache.cpp

@@ -37,7 +37,7 @@
 namespace Magnum { namespace Text {
 
 DistanceFieldGlyphCache::DistanceFieldGlyphCache(const Vector2i& originalSize, const Vector2i& size, const UnsignedInt radius):
-    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES3)
+    #if !(defined(MAGNUM_TARGET_GLES) && defined(MAGNUM_TARGET_GLES2))
     GlyphCache(TextureFormat::R8, originalSize, size, Vector2i(radius)),
     #elif !defined(MAGNUM_TARGET_WEBGL)
     /* Luminance is not renderable in most cases */
@@ -60,7 +60,7 @@ DistanceFieldGlyphCache::DistanceFieldGlyphCache(const Vector2i& originalSize, c
 }
 
 void DistanceFieldGlyphCache::setImage(const Vector2i& offset, const ImageReference2D& image) {
-    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES3)
+    #if !(defined(MAGNUM_TARGET_GLES) && defined(MAGNUM_TARGET_GLES2))
     const TextureFormat internalFormat = TextureFormat::R8;
     CORRADE_ASSERT(image.format() == ColorFormat::Red,
         "Text::DistanceFieldGlyphCache::setImage(): expected" << ColorFormat::Red << "but got" << image.format(), );
@@ -91,7 +91,7 @@ void DistanceFieldGlyphCache::setImage(const Vector2i& offset, const ImageRefere
 }
 
 void DistanceFieldGlyphCache::setDistanceFieldImage(const Vector2i& offset, const ImageReference2D& image) {
-    #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES3)
+    #if !(defined(MAGNUM_TARGET_GLES) && defined(MAGNUM_TARGET_GLES2))
     CORRADE_ASSERT(image.format() == ColorFormat::Red,
         "Text::DistanceFieldGlyphCache::setDistanceFieldImage(): expected" << ColorFormat::Red << "but got" << image.format(), );
     #else

src/Magnum/TextureFormat.h

@@ -648,7 +648,7 @@ enum class TextureFormat: GLenum {
      */
     RGB565 = GL_RGB565,
 
-    #if !defined(MAGNUM_TARGET_GLES3) && !defined(MAGNUM_TARGET_WEBGL)
+    #if !defined(MAGNUM_TARGET_GLES) || (defined(MAGNUM_TARGET_GLES2) && !defined(MAGNUM_TARGET_WEBGL))
     /**
      * RGB, each component normalized unsigned 10bit.
      * @requires_es_extension Extension @es_extension{EXT,texture_type_2_10_10_10_REV}