refactor: reorder checkLVal parameters

[JLHwung]

Q	A
Bug Fix	Babel should throw const let = 1 when typescript plugin is enabled (bug)
License	MIT

This PR aims to simplify checkLVal usage and tweaked storage of checkClashes a bit. It unintentionally fixed a parser bug.

While working on this PR, I find a bug of estree plugin:

// should throw when 'estree' is enabled
(arguments) => { "use strict"; }

This PR does not fix this bug. It should have been caught by the estree-throws parser tests,

babel/packages/babel-parser/test/helpers/runFixtureTests.js

Line 86 in 5bbad89

if (!task.options.throws) return;

but then I realize estree-throws will eventually become noop as we are now testing parser on error recovery mode. I will address that in another PR.

[JLHwung]

Implement checkClashes with Set so we don't have to deal with old V8 bug.

[babel-bot]

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[JLHwung]

Passing through all the rest parameters here causes typescript-parser tests failed: https://travis-ci.com/github/babel/babel/jobs/433402908#L842

Ironically this is a bug fix, let's see one of the failing tests

https://github.com/microsoft/TypeScript/blob/b5b0437a86661c8d7bc76c5860c07305df17899c/tests/cases/compiler/letInConstDeclarations_ES5.ts#L1-L8

It should fail but TS compiler is so loose that it allows such cases, just to be thrown later by TS type checking diagnostics. I will add them to the allowlist.