Use NodeFlags to detect nodes inside with statements instead of climbing ancestors

[ghost]

Previously, every time we needed to know whether a node was in a with statement, we would climb all of its ancestor nodes looking for a with statement. Since there usually wasn't one, this would take a while.

Now we just add a NodeFlags for this during parsing. This is similar to the optimization done to detect whether we're in JSDoc. (#17176 (comment))

This appears to give a 1% average improvement in performance in the checker, without any major slowdown in the parser.

Monaco - node (v8.2.1, x64)

Project	Baseline	Current	Delta	Best	Worst
Memory used	356,983k (± 0.01%)	356,966k (± 0.01%)	-17k (- 0.00%)	356,905k	357,082k
Parse Time	2.12s (± 0.69%)	2.12s (± 0.50%)	-0.00s (- 0.09%)	2.10s	2.15s
Bind Time	0.82s (± 0.63%)	0.82s (± 0.75%)	+0.00s (+ 0.24%)	0.81s	0.83s
Check Time	4.30s (± 0.59%)	4.17s (± 0.49%)	-0.13s (- 3.03%)	4.12s	4.20s
Emit Time	2.80s (± 1.40%)	2.76s (± 0.96%)	-0.03s (- 1.11%)	2.73s	2.85s
Total Time	10.03s (± 0.74%)	9.87s (± 0.41%)	-0.16s (- 1.63%)	9.78s	9.94s

Monaco - tsc (x86)

Project	Baseline	Current	Delta	Best	Worst
Parse Time	1.48s (± 1.10%)	1.49s (± 0.59%)	+0.01s (+ 0.40%)	1.47s	1.51s
Bind Time	0.57s (± 2.08%)	0.58s (± 2.56%)	+0.01s (+ 1.40%)	0.55s	0.62s
Check Time	4.04s (± 1.97%)	3.96s (± 1.13%)	-0.08s (- 2.01%)	3.86s	4.03s
Emit Time	7.65s (± 3.77%)	7.59s (± 0.99%)	-0.06s (- 0.81%)	7.52s	7.86s
Total Time	13.75s (± 2.26%)	13.62s (± 0.72%)	-0.13s (- 0.96%)	13.45s	13.87s

TFS - node (v8.2.1, x64)

Project	Baseline	Current	Delta	Best	Worst
Memory used	309,625k (± 0.01%)	309,627k (± 0.01%)	+3k (+ 0.00%)	309,542k	309,666k
Parse Time	1.54s (± 2.26%)	1.55s (± 2.43%)	+0.00s (+ 0.13%)	1.44s	1.58s
Bind Time	0.70s (± 5.85%)	0.70s (± 5.63%)	-0.00s (- 0.71%)	0.66s	0.81s
Check Time	3.68s (± 0.42%)	3.68s (± 1.73%)	+0.00s (+ 0.05%)	3.61s	3.93s
Emit Time	2.45s (± 0.34%)	2.46s (± 0.55%)	+0.01s (+ 0.24%)	2.44s	2.49s
Total Time	8.38s (± 0.29%)	8.38s (± 0.77%)	+0.00s (+ 0.05%)	8.30s	8.62s

TFS - tsc (x86)

Project	Baseline	Current	Delta	Best	Worst
Parse Time	1.07s (± 1.78%)	1.08s (± 1.52%)	+0.00s (+ 0.47%)	1.05s	1.12s
Bind Time	0.57s (± 4.34%)	0.58s (± 2.75%)	+0.01s (+ 1.22%)	0.53s	0.61s
Check Time	3.29s (± 1.79%)	3.26s (± 1.71%)	-0.03s (- 0.82%)	3.16s	3.41s
Emit Time	4.53s (± 1.59%)	4.47s (± 0.87%)	-0.06s (- 1.32%)	4.39s	4.57s
Total Time	9.46s (± 0.90%)	9.39s (± 0.70%)	-0.07s (- 0.78%)	9.26s	9.53s

[ghost]

@rbuckton Any comments?

[ghost]

@rbuckton Good to go?

[ghost]

@rbuckton Bump