The enumerable expression in a for-in/of loop is supposed to have a TDZ for any
lexically bound names in that loop (there can be more than one with destructuring).
This patch accomplishes this with an almost-correct desugaring. The only thing missing
is proper debugger support (the let declarations added by the desugaring, while invisible
to code due to shadowing, are visible to the debugger).
BUG=v8:4210
LOG=n
Review URL: https://codereview.chromium.org/1218543003
Cr-Commit-Position: refs/heads/master@{#29396}
Also support patterns in ``for (var p in/of ...)``
This CL extends the rewriting we used to do for ``for (let p in/of...)`` to
``for (var p in/of ...)``. For all for..in/of loop declaring variable,
we rewrite
for (var/let/const pattern in/of e) b
into
for (x' in/of e) { var/let/const pattern = e; b }
This adds a small complication for debugger: for a statement
for (var v in/of e) ...
we used to have
var v;
for (v in/of e) ...
and there was a separate breakpoint on ``var v`` line.
This breakpoint is actually useless since it is immediately followed by
a breakpoint on evaluation of ``e``, so this CL removes that breakpoint
location.
Similiraly, for let, it used to be that
for (let v in/of e) ...
became
for (x' in/of e) { let v; v = x'; ... }
``let v``generetaed a useless breakpoint (with the location at the
loop's head. This CL removes that breakpoint as well.
R=arv@chromium.org,rossberg@chromium.org
BUG=v8:811
LOG=N
Review URL: https://codereview.chromium.org/1149043005
Cr-Commit-Position: refs/heads/master@{#28565}
