Added assert that assetref is of type ExternalURL by the time HttpAssetProvider gets a RequestAsset.
Added assert that assetref is of type ExternalURL by the time HttpAssetProvider gets a RequestAsset.

jesterKing/naali,BogusCurry/tundra,BogusCurry/tundra,BogusCurry/tundra,AlphaStaxLLC/tundra,pharos3d/tundra,AlphaStaxLLC/tundra,jesterKing/naali,AlphaStaxLLC/tundra,pharos3d/tundra,BogusCurry/tundra,jesterKing/naali,BogusCurry/tundra,jesterKing/naali,realXtend/tundra,AlphaStaxLLC/tundra,jesterKing/naali,pharos3d/tundra,BogusCurry/tundra,jesterKing/naali,AlphaStaxLLC/tundra,AlphaStaxLLC/tundra,pharos3d/tundra,realXtend/tundra,pharos3d/tundra,realXtend/tundra,realXtend/tundra,pharos3d/tundra,realXtend/tundra,jesterKing/naali,realXtend/tundra