Endermen don't become aggressive when players look at their head/feet

Only looking at their torso will make them become aggressive at you.

Step to reproduce:
Go in a Survival world
Find an enderman
Stare at him.

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Code analysis: https://bugs.mojang.com/browse/MC-87907?focusedCommentId=300590&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-300590