fix(legacy): suppress babel warning during polyfill scan

[kingyue737]

Description

Babel throws the following warning during building which is quite annoying:

[BABEL] Note: The code generator has deoptimised the styling of undefined as it exceeds the max of 500KB.

I think we can simply turn on compact option when detecting polyfills. Just like what Evan previous did in 045e519

fixes #7907

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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