[es6] Function.prototype.name should be the empty string

[es6] Function.prototype.name should be the empty string

ES6 specifies the function name property (it was not part of ES5) and
it specifies the name of Function.prototype to the empty string ("" and
not "Empty"). This makes us match Firefox, Safari and IE developer
preview.

BUG=v8:4033
LOG=N
R=adamk@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1080393004

Cr-Commit-Position: refs/heads/master@{#28021}