1764773 - Do not use global this to define global variable in jsm

Status: RESOLVED DUPLICATE of bug 1610653

(Firefox :: General, task, P3)

Description

[Tooru Fujisawa [:arai]]

As a preparation for esmification, global this usage needs to be reduced.

There are several case that global variable is defined by this.foo = ..., but it can be rewritten as var foo = ....

This bug does not cover the case that copies lexical variable to global variable, because that cannot be rewritten until we switch to ES module:
Some other code does the following to copy lexical variable to global variable, but this is not necessary to export.

const foo = 10;
this.foo = foo;