Reduce size of compiled code skipping unused helpers

*tiny fix* README.md: coveralls - switch branch to master

The link mistakenly linked to a development branch.

Previously those were preloaded for every file, this saves some bytes:

BEFORE:
development: 77...

Each file can load an internal helper without requiring it to be
available for every single comp...

Allowing magic comments to have complex values will make the good
vehicles for method names and ...

Chrome runner fixes

This works better with opal-rspec.

Was failing most of the time by a few seconds.

Fix Number#round for Integers

Fix nested for-loops

Fixes #2033

Fixing a small mistake which triggered my closure compiler.

Was:
>> 8099.round(-1)
=> NaN
...

Allow calling define_method from the top object

Typo, was supposed to be "use strict";

MRI defines it on the singleton object and makes it a proxy for
Object.define_method. This imple...

Add per-file "use strict" support

Update to JRuby 9.2.9.0.

This is more consistent with what's done by MRI.

Moving towards strict-mode string literals won't be upgraded to boxed
object when inside methods...

It also generates less code, resulting in a smaller size.

---

⤑ bin/opal-benchmark-ips benchma...

Options are frequently fetched and can benefit from memoization.

Let's save some work if it's not needed.

It's easier on the eye.

Will put a "use strict" mark at the top of the files anonymous
function marking the file's conte...

This is mandatory in strict mode because that property is not writable
by default.

In strict-mode primitive values are not boxed within their methods.

E.g. 0 is falsy as a value ...

Fix bugs and add a spec for the server runner

Update Bundler lock files, remove usage of deprecated APIs and let
the Rack example do something...

Runtime fixes, courtesy of @Mogztter

This is in preparation for when we'll enable "use strict".

benchmarking.rake - bench:ips - correct a path to benchmarks

This instruction was probably originally in a Rakefile and so it referenced __dir__ correctly. A...

Used parser version is incompatible with rubocop

Add Opal::Compiler#magic_comment_flags

Using `next` isn't always the best and most readable solution.

Will allow access to magic-comments nicely converting them to a hash.

Remove legacy runner API

Get them out of the legacy API and extract the common code.

Update submodules

Remove workaround targeted at JRuby 1.7

At this moment the current JRuby version is 9.2.8.0, so should be safe
to assume we're good now.

Fix Module#attr with multiple arguments

Resolves #2003

This will better reflect the original C code by also adding a warning
and a single fallback case.

Update to latest Rubocop

Update to latest mspec & ruby specs

Remove duplicates from .rubocop.yml

As it's not compatible with --parallel.

Also get rid of bigdecimal/kernel and embed the method definition in
the main file.

Passing `uplevel:` prints a warning with the same format as those
printed by the corelib.

Add a simple filters formatter

Ensure filters are always sorted and formatted consistently.

- Removes duplicates ignoring the ...

[skip ci]

opal 1.0 fix: raises "warning: Removed semicolon ending x-string expression,...

[skip ci]

Add opal/io to opal/mini

Related to #1481 and #1466.

Remove duplicated spec filter

Allow to change Nashorn path if using GraalVM

See also:
- https://github.com/graalvm/graaljs/blob/master/docs/user/NashornMigrationGuide.md#la...

Move the compiler runner to its own file