Rollup incorrectly eliminates conditions on object properties set through 'this'

[ashmind]

• Rollup Version: 0.66.2
• Operating System (or Browser): Reproducible in Repl on Chrome 69 Win
• Node Version: N/A (Repl)

How Do We Reproduce?

https://rollupjs.org/repl?version=0.66.2&shareable=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

Expected Behavior

Logic in hideIfActive is preserved, as there are valid situations where o.active would be true.
E.g: if show() is called first.

Actual Behavior

hideIfActive is emptied, which breaks the logic (now you can't hide o when it's active).

[kzc]

Related issue: #2345

Tree shaking can be disabled as a workaround or use one of the patches in link above.

[shellscape]

This is still a valid bug in the latest version of the Rollup REPL.