clang-format: [JS] do not break in ArrayType[].

Summary:
Wrapping between the type name and the array type indicator creates
invalid syntax in TypeScript.

Before:
    const xIsALongIdent:
        YJustBarelyFitsLinex
            [];  // illegal syntax.

After:
    const xIsALongIdent:
        YJustBarelyFitsLinex[];

Reviewers: djasper

Subscribers: klimek

Differential Revision: https://reviews.llvm.org/D40436

llvm-svn: 318959