@angular-devkit/build-angular@6.1.0-rc.2 output doesn't for on Firefox<50

[suau]

Bug Report or Feature Request (mark with an x)

- [x] bug report -> please search issues before submitting
- [ ] feature request

Area

- [x] devkit
- [ ] schematics

Versions

npm 6.1.0
macOS 10.13.4
@angular/cli@6.1.0-rc.2
@angular-devkit/build-angular@6.1.0-rc.2

Repro steps

• bootstrap a new project with angular-cli
• build the project with the --prod flag
• serve it with your favorite server
• open in Firefox < 50
• check the developer console for errors

The log given by the failure

the main bundle with crash with a SyntaxError

Desired functionality

the project should run properly

Mention any other details that might be useful

This is the bug behind it: #9340
The issue seems to be with uglify-es>3.2.2
Pinning the version of uglifyjs-webpack-plugin to 1.1.5 in @angular-devkit/build-angular would resolve it.

[filipesilva]

Heya, I'm going to close this issue in favor of #9340 since that seems to be the main one. I'll ping the team about this though.

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