ES6 specs the function length property (it was not part of ES5) and
it makes it configurable.
BUG=v8:3045
LOG=N
R=mstarzinger@chromium.org, adamk@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/993073002
Cr-Commit-Position: refs/heads/master@{#27190}
ES6 makes the Function object properties "length" and "name"
configurable; switch the implementation over to follow that.
Doing so exposed a problem in the handling of non-writable, but
configurable properties backed by foreign callback accessors
internally. As an optimization, if such an accessor property is
re-defined with a new value, its setter was passed the new value
directly, keeping the property as an accessor property. However, this
is not correct should the property be non-writable, as its setter will
then simply ignore the updated value. Adjust the enabling logic for
this optimization accordingly, along with adding a test.
LOG=N
R=rossberg@chromium.org, rossberg
BUG=v8:3045
Review URL: https://codereview.chromium.org/116083006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19200 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
