GL: these entrypoints are never used on WebGL 1, compile them out.

src/Magnum/GL/AbstractFramebuffer.cpp

@@ -499,18 +499,14 @@ void AbstractFramebuffer::copySubImage(const Range2Di& rectangle, CubeMapTexture
 }
 #endif
 
+#if !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
 void AbstractFramebuffer::invalidateImplementationNoOp(AbstractFramebuffer&, GLsizei, const GLenum* const) {}
 
 void AbstractFramebuffer::invalidateImplementationDefault(AbstractFramebuffer& self, const GLsizei count, const GLenum* const attachments) {
     #ifndef MAGNUM_TARGET_GLES2
     glInvalidateFramebuffer(GLenum(self.bindInternal()), count, attachments);
-    #elif !defined(CORRADE_TARGET_EMSCRIPTEN)
-    glDiscardFramebufferEXT(GLenum(self.bindInternal()), count, attachments);
     #else
-    static_cast<void>(self);
-    static_cast<void>(count);
-    static_cast<void>(attachments);
-    CORRADE_INTERNAL_ASSERT_UNREACHABLE(); /* LCOV_EXCL_LINE */
+    glDiscardFramebufferEXT(GLenum(self.bindInternal()), count, attachments);
     #endif
 }
 
@@ -519,6 +515,7 @@ void AbstractFramebuffer::invalidateImplementationDSA(AbstractFramebuffer& self,
     glInvalidateNamedFramebufferData(self._id, count, attachments);
 }
 #endif
+#endif
 
 #ifndef MAGNUM_TARGET_GLES2
 void AbstractFramebuffer::invalidateImplementationNoOp(AbstractFramebuffer&, GLsizei, const GLenum*, const Range2Di&) {}

src/Magnum/GL/AbstractFramebuffer.h

@@ -891,11 +891,13 @@ class MAGNUM_GL_EXPORT AbstractFramebuffer {
         static void MAGNUM_GL_LOCAL copySub3DImplementationDSA(const Range2Di& rectangle, AbstractTexture& texture, Int level, const Vector3i& offset);
         #endif
 
+        #if !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
         static void MAGNUM_GL_LOCAL invalidateImplementationNoOp(AbstractFramebuffer& self, GLsizei, const GLenum*);
         static void MAGNUM_GL_LOCAL invalidateImplementationDefault(AbstractFramebuffer& self, GLsizei count, const GLenum* attachments);
         #ifndef MAGNUM_TARGET_GLES
         static void MAGNUM_GL_LOCAL invalidateImplementationDSA(AbstractFramebuffer& self, GLsizei count, const GLenum* attachments);
         #endif
+        #endif
 
         #ifndef MAGNUM_TARGET_GLES2
         static void MAGNUM_GL_LOCAL invalidateImplementationNoOp(AbstractFramebuffer& self, GLsizei, const GLenum*, const Range2Di&);