Regression tests
Add retyper test
Batch compiler scenario fixes for 0.9.0
Several fixes for regressions in generic specialization and type argument inference
Update genericCombinators fourslash tests to reflect recent bug fixes
Fix checking of generic constraints against previous type arguments
Remove special-casing of array types when checking for the presence of type arguments at a reference site
Prevent value name symbols from being cached if they resolved to 'any' - we may need to contextually type them later
Merge from release-0.9.0
Web harness work.
Break the tree-to-ast visitor into two paths.  One for incremental and one for non incremental scenarios.

This helps speed up ast translation by about 25%.
Update webharness.
Update fidelity test suite.
Flatten AST nodes even more to shave another couple of % off batch parse time.
Improve AST conversion perf by avoiding walking to the same token multiple times.
Directly get the last token, as calling .lastToken is actually showing up in traces.
Use fixed size arrays when we know the number of elements we'll be putting in them.
Use array constructor over array literals.
Construct more objects completely up front.  Also, reduce the number of reads and writes to an object.
Remove unnecessary field in AST node.  This saves a lookup during construction.