Use our own scanner for 'isNumericName'.
Handle numeric signs in 'isNumericName'.

To be fair, I don't think humanity knew about negative numbers until like 200 B.C.E.
Ensure that numeric names are in their printed form.
Quick edit to comment.
Merge branch 'master' into numbersAreHard

Conflicts:
	tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt
Make things more conformant with 9.8.1 of EC-262 spec.

Specifically, a numeric property is simply now any property whose name N is equal to ToString(ToNumber(N)).
Explain what is happening in 'isNumericName'.
More comments.
Merge branch 'master' into numbersAreHard

Conflicts:
	src/compiler/checker.ts
	tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations.errors.txt
	tests/baselines/reference/numericIndexerConstrainsPropertyDeclarations2.errors.txt
Merge pull request #860 from Microsoft/numbersAreHard

Take runtime semantics of numerically named properties into account.