[es6] Move builtin constructors for primitives to strict mode.

[es6] Move builtin constructors for primitives to strict mode.

The ES6 specification says that "Built-in functions that are ECMAScript
function objects must be strict mode functions", which in particular
means that you can never test for them using the "caller" field of a
sloppy mode function.

CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_linux_layout_dbg,v8_linux_nosnap_dbg
R=mstarzinger@chromium.org
BUG=v8:105
LOG=n

Review URL: https://codereview.chromium.org/1347663002

Cr-Commit-Position: refs/heads/master@{#30750}