Move data from Completion and ExpressionResult to context

[lahma]

Small steps towards returning data using context instead of structs. Target is a prime example of returning possible jump instruction via completion which is not needed in 99% of the cases.

Tests seem to have quite the jitter, but show that we are moving to the right direction.

Jint.Benchmark.DromaeoBenchmark

Diff	Method	FileName	Mean	Error	Allocated
Old	Run	dromaeo-3d-cube	27.893 ms	0.0420 ms	7166.38 KB
New			26.489 ms (-5%)	0.0326 ms	7164.43 KB (0%)
Old	Run	dromaeo-core-eval	7.049 ms	0.0172 ms	320.64 KB
New			7.304 ms (+4%)	0.0526 ms	319.54 KB (0%)
Old	Run	dromaeo-object-array	81.914 ms	0.3203 ms	106133.43 KB
New			84.156 ms (+3%)	0.1687 ms	106134.6 KB (0%)
Old	Run	droma(...)egexp [21]	315.073 ms	6.1587 ms	235918.41 KB
New			307.709 ms (-2%)	2.6667 ms	234367.11 KB (-1%)
Old	Run	droma(...)tring [21]	468.829 ms	34.3012 ms	1331640.95 KB
New			438.789 ms (-6%)	31.2505 ms	1331443.9 KB (0%)
Old	Run	droma(...)ase64 [21]	75.731 ms	0.6149 ms	7789.08 KB
New			72.038 ms (-5%)	0.1586 ms	7790.63 KB (0%)
Old	Run	dromaeo-3d-cube	26.340 ms	0.0479 ms	6871.89 KB
New			25.802 ms (-2%)	0.0327 ms	6869.94 KB (0%)
Old	Run	dromaeo-core-eval	7.048 ms	0.0177 ms	308 KB
New			7.690 ms (+9%)	0.0231 ms	306.9 KB (0%)
Old	Run	dromaeo-object-array	84.917 ms	0.2181 ms	106094.9 KB
New			81.887 ms (-4%)	0.2789 ms	106095.02 KB (0%)
Old	Run	droma(...)egexp [21]	313.301 ms	6.1554 ms	234390.18 KB
New			308.210 ms (-2%)	2.1133 ms	242594.01 KB (+4%)
Old	Run	droma(...)tring [21]	433.911 ms	32.3667 ms	1331568.45 KB
New			400.063 ms (-8%)	18.8510 ms	1331583.32 KB (0%)
Old	Run	droma(...)ase64 [21]	75.744 ms	0.3382 ms	7701.19 KB
New			69.859 ms (-8%)	0.1002 ms	7701.22 KB (0%)