Shaders: make instancing finally work on ES2 / WebGL 1.

This was stupid, eh? Blame Mesa and SwiftShader for not exposing
ANGLE_instanced_arrays so the only way to test this for me was via the
browser, which is practically impossible. Then found this by an
accident.

Pushing straight to master because YOLO.

src/Magnum/Shaders/Flat.cpp

@@ -109,11 +109,11 @@ template<UnsignedInt dimensions> Flat<dimensions>::Flat(const Flags flags): _fla
         }
         if(flags >= Flag::InstancedObjectId)
             bindAttributeLocation(ObjectId::Location, "instanceObjectId");
+        #endif
         if(flags & Flag::InstancedTransformation)
             bindAttributeLocation(TransformationMatrix::Location, "instancedTransformationMatrix");
         if(flags >= Flag::InstancedTextureOffset)
             bindAttributeLocation(TextureOffset::Location, "instancedTextureOffset");
-        #endif
     }
     #endif
 

src/Magnum/Shaders/Phong.cpp

@@ -154,11 +154,11 @@ Phong::Phong(const Flags flags, const UnsignedInt lightCount): _flags{flags}, _l
         }
         if(flags >= Flag::InstancedObjectId)
             bindAttributeLocation(ObjectId::Location, "instanceObjectId");
+        #endif
         if(flags & Flag::InstancedTransformation)
             bindAttributeLocation(TransformationMatrix::Location, "instancedTransformationMatrix");
         if(flags >= Flag::InstancedTextureOffset)
             bindAttributeLocation(TextureOffset::Location, "instancedTextureOffset");
-        #endif
     }
     #endif