Shaders: F_Schlick dotLH -> dotVH

[WestLangley]

For consistency with #21927, these changes are warranted.

/ping @sunag Note dotLH = dotVH, so this change is for semantics only.

[sunag]

Thank you for letting me know . Currently it is like this for new NodeMaterial system:

three.js/examples/jsm/renderers/nodes/functions/BSDFs.js

Lines 44 to 51 in efa1b47

	vec3 halfDir = normalize( lightDirection + PositionViewDirection );
	//float dotNL = saturate( dot( NormalView, lightDirection ) );
	//float dotNV = saturate( dot( NormalView, PositionViewDirection ) );
	float dotNH = saturate( dot( NormalView, halfDir ) );
	float dotLH = saturate( dot( lightDirection, halfDir ) );
	vec3 F = F_Schlick( specularColor, dotLH );

But I can update too.

[WestLangley]

Merging for now... I hope that is OK...

[mrdoob]

Thanks!