Update webkit to 2.22.2

[wkozyra95]

webkit update fixes #50

[kmagiera]

@wkozyra95 can you post here some details about what the footprint look like with DFG comparing to builds of the previous version of JSC?

[wkozyra95]

In terms of binary size (without intl)

sizes for intl build ver 2.18:

type	armv7	arm64
no DFG no FTL	4.7 MB	5.0 MB
no FTL with DFG	5.3 MB	5.7 MB

sizes for intl build ver 2.22.2 arm64:

type	armv7	arm64
no DFG no FTL	n/a	n/a
no FTL with DFG	6.0 MB	6.4 MB

The size was calculated for striped and zipped *.so file.

As for runtime performance, most of the benchmark results I saw was not trustworthy because I ran benchmarks one after another usually for a longer period and android seems to throttle down apps that use that much resources.

For a first few runs, I noticed that

• sunspider was about 20-30% faster
• jetstream was 3 times faster

From what I remember the rest of the benchmarks was more or less the same as 32-bit version.
I was mostly focused on checking whether there is no performance degradation. I'll post exact values when I have a chance.

EDIT: Updated binary size with intl enabled

[DanielZlotin]

I'm testing this out, measuring etc.

[DanielZlotin]

The revision number is wrong but I'll fix it,
so far looks good!
I'll accept the PR, run the full suite and if everything is good I'll publish the new version

[wkozyra95]

arm7 no DFG (10 times)

"tti": "3613",
"sunspider": "787",
"jetstream": "5099",
"octane2": "2946",
"sixspeed": "610",
"renderflat": "1580",
"renderdeep": "2511",

arm64 with DFG (10 times)

"tti": "3640",
"sunspider": "579",
"jetstream": "824",
"octane2": "1716",
"sixspeed": "491",
"renderflat": "1374",
"renderdeep": "2640",