This removes the --turbo flag and solely relies on the filter pattern
provided via --turbo-filter when deciding whether to use TurboFan. Note
that disabling optimization wholesale can still be done with --no-opt,
which should be used in favor of --no-turbo everywhere.

Also note that this contains semantic changes to the TurboFan activation
criteria. We respect the filter pattern more stringently and no longer
activate TurboFan just because the source contains patterns forcing use
of Ignition via {AstNumberingVisitor::DisableFullCodegenAndCrankshaft}.

R=rmcilroy@chromium.org
BUG=v8:6408

Change-Id: I0c855f6a62350eb62283a3431c8cc1baa750950e
Reviewed-on: https://chromium-review.googlesource.com/528121Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46167}

Once we enabled --turbo by default we need to turn all the implications
off with --no-turbo as well. Chrome sets flags in V8 using SetFlagFromString,
which enforces the implications each time it is called. Therefore, if --turbo
is enabled by default, and an unrelated flag is set, the turbo implications are
enabled but not later disabled if we set --no-turbo. To fix this, add negative
implications as well.

BUG=chromium:692409

Change-Id: Iadb0ca542f49ba65c7419cda8c7a03636a8d5ba9
Reviewed-on: https://chromium-review.googlesource.com/451320
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43655}

This commit introduces IgnitionStatisticsExtension, which provides
methods for accessing Ignition statistics and counters from JavaScript.

The extension is registered when FLAG_ignition and
FLAG_trace_ignition_dispatches are both enabled.

For the moment, the only exposed function is
getIgnitionDispatchCounters(), which allows to retrieve Ignition
dispatch counters as a JavaScript object.

BUG=v8:4899
LOG=N

Review URL: https://codereview.chromium.org/1899133004

Cr-Commit-Position: refs/heads/master@{#35816}