Update dependency terser-webpack-plugin to v2

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
terser-webpack-plugin	devDependencies	major	1.4.1 -> 2.0.0

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Release Notes

webpack-contrib/terser-webpack-plugin

v2.0.0

Compare Source

⚠ BREAKING CHANGES

• minimum require Node.js version is 8.9.0
• the extractComments option is true by default
• the cache option is true by default
• the parallel option is true by default
• using the extractComments.condition option with true value extract only some comments

Bug Fixes

• do not run parallel mode when you have only one file (#​134) (8b88b39)
• make extractComments API more consistent (#​129) (37d2df0)
• parallel on wsl (#​138) (0537591)

Features

• enable the cache option by default (#​132) (960d249)
• enable the extractComments option by default (ad2471c)
• enable the parallel option by default (#​131) (7b342af)
• respect devtool values for source map generation (#​140) (dd37ca1)

1.4.1 (2019-07-31)

Bug Fixes

• removed unnecessary dependency (#​111) (bc19b72)

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[coveralls]

Pull Request Test Coverage Report for Build 1999

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 1997:	0.0%
Covered Lines:	95
Relevant Lines:	95

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💛 - Coveralls