Removed unused name_ field, made bitfield 16-bits long, and moved it to
the start of the struct, resulting in a reduction of 8 bytes on both
32 and 64-bit platforms.

Most other changes (which prompted this work) are cosmetic:r
  - Combined redundant enums
  - Named enum values kConsistently
  - Consistently use booleans in bitfield, using enum values
    only for passing information into NewFunctionLiteral
  - Removed unneeded arguments from NewFunctionLiteral, reducing
    clutter at callsites
  - Added const correctness consistently

Review URL: https://codereview.chromium.org/1566053002

Cr-Commit-Position: refs/heads/master@{#33194}