This is a reland of ed6f00fb
Original change's description:
> [modules] Implement import.meta proposal
> 
> Rewrites references to import.meta to a new GetImportMetaObject runtime
> call. Embedders can define a callback for creating the meta object using
> v8::Isolate::SetHostGetImportMetaObjectCallback. If no callback has been
> provided, an empty object with null prototype is created.
> 
> This adds an example implementation to d8 that sets meta.url.
> 
> Bug: v8:6693
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: I6871eec79da45bba81bbbc84b1ffff48534c368d
> Reviewed-on: https://chromium-review.googlesource.com/707902
> Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48433}

TBR=adamk@chromium.org

Bug: v8:6693
Change-Id: Ie2d746ad996a56ed6ff50b832f320fe44e02f231
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/712834Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48468}

New test262 tests bring up a couple cases with async arrow functions
that V8 didn't seem to handle properly; this patch makes those cases
errors:
- async (...x,) => y -- Rest parameter must be last formal parameter
- async (...x = z) => y -- No default value for rest parameter
- async (...x, y) => z -- Rest parameter must be last formal parameter

Bug: v8:4483, v8:5051
Change-Id: I024d9ba0c854e8e5e75283df2ee53127b1be090d
Reviewed-on: https://chromium-review.googlesource.com/496057
Commit-Queue: Daniel Ehrenberg <littledan@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#45116}

Bug: v8:6337
Change-Id: I7de330c77e5f4cbb2cd4bf327c8b60783e78880c
Reviewed-on: https://chromium-review.googlesource.com/493786
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45043}

This patch implements the runtime semantics of dynamic import.

We create a new ASTNode so that we can pass the JSFunction closure() to
the runtime function from which we get the script_url.

d8 implements the embedder logic required to load and evaluate the modules.

The API is mostly implemented as specified.

BUG=8:5785

Review-Url: https://codereview.chromium.org/2703563002
Cr-Commit-Position: refs/heads/master@{#44551}

https://codereview.chromium.org/2694003002/ introduced
"SyntaxError: Lexical declaration cannot appear in a single-statement context"
for the case when let + desctructuring from a list happen.

As was pointed out in https://codereview.chromium.org/2694003002/#msg18, the
case without destructuring would also benefit from a better message: if a
single statement is expected and "let identifier = ..." is seen, the error is
indeed again that the lexical declaration is not a statement. However, the current
error is "Unexpected identifier", because the parser tries to accept "let" as
an identifier in an expression statement, and then gives up seeing the other
identifier after "let".

This CL ensures that the parser recognises the error properly and reports
accordingly. It also renames the existing test, which contains destructuring,
and adds the one with a non-destructuring lexical declaration.

BUG=v8:5686

Review-Url: https://codereview.chromium.org/2697193007
Cr-Commit-Position: refs/heads/master@{#43275}

ES2017 forbids the sequence of tokens "let [" in in expression statements [1].

This CL makes ParserBase report those instances as SyntaxError. It also adds a
customised error message for that, because the standard "Unexpected token" is
not applicable: "let" itself is not forbidden in those context, only the
sequence of "let [".

[1] https://tc39.github.io/ecma262/#sec-expression-statement

BUG=v8:5686

Review-Url: https://codereview.chromium.org/2694003002
Cr-Commit-Position: refs/heads/master@{#43258}

TBR=tebbi@chromium.org
BUG=chromium:679841

Review-Url: https://codereview.chromium.org/2631163002
Cr-Commit-Position: refs/heads/master@{#42375}

The bug was caused by AstTraversalVisitor refactoring:
https://codereview.chromium.org/2169833002/

InitializerRewriter::VisitRewritableExpression in parser.cc didn't recurse; so
it fails when a rewritable expression contains another rewritable expression.

See the bug for more details.

BUG=chromium:679727

Review-Url: https://codereview.chromium.org/2629623002
Cr-Commit-Position: refs/heads/master@{#42274}

R=bmeurer@chromium.org
BUG=chromium:677757

Review-Url: https://codereview.chromium.org/2606383005
Cr-Commit-Position: refs/heads/master@{#42066}