Fixed emission material properties not being animable

[alelievr]

Purpose of this PR

Fix the emission properties of material not being animable from the inspector (https://fogbugz.unity3d.com/f/cases/1328108/)

Note that even though now we can animate these properties, the feature is STILL broken because of another issue:

Emission.mp4

As you can see in the video, the intensity of the emission is completely different when animated. But this has nothing to do with animation, in fact is seems to come from the material property block of the renderer. I managed to repro the issue with this simple script:

[ExecuteAlways]
public class SetEmission : MonoBehaviour
{
    [ColorUsage(false, true)]
    public Color emissionColor;

    public bool useMaterialPropertyBlock = false;

    new MeshRenderer renderer;

    void Start()
    {
        renderer = GetComponent<MeshRenderer>();
    }

    void Update()
    {
        if (useMaterialPropertyBlock)
        {
            var p = new MaterialPropertyBlock();
            p.SetColor("_EmissiveColor", emissionColor);
            renderer.SetPropertyBlock(p);
        }
        else
        {
            var p = new MaterialPropertyBlock();
            renderer.SetPropertyBlock(p);
            renderer.sharedMaterial.SetColor("_EmissiveColor", emissionColor);
        }
    }
}

new fogbugz about the material property block issue: https://fogbugz.unity3d.com/f/cases/1332471/

---

Testing status

manual tests (see video)

[adrien-de-tocqueville]

I believe the decal material editor has the same issue because they also use UpdateEmissiveColorLDRFromIntensityAndEmissiveColor

[alelievr]

It's not possible to animate material on the decal projector component, this feature only works with Renderers (which is a shame)

[iM0ve]

Thanks for providing the video of testing. I can see the emission still works and now we can animate the property. Also new bug filled about the intensities, nice!