[cursor] don't add canvas listeners if downEvents/upEvents defined (#3296)
[cursor] don't add canvas listeners if downEvents/upEvents defined (#3296)


RSpace/aframe,chenzlabs/aframe,aframevr/aframe,dmarcos/aframe,RSpace/aframe,wizgrav/aframe,ngokevin/aframe,mkungla/aframe,chenzlabs/aframe,wizgrav/aframe,dmarcos/aframe,aframevr/aframe,mkungla/aframe,ngokevin/aframe