layer try/except blocks

[disruptek]

We should layer statements in each block so that we can accumulate state without breaking scope and still catch exceptions. This will unify var x = foo() statements with the rest of the tests.

var x = foo()
test2()

...turns into...

try:
  var x = foo()
  try:
     test2()
  except: ...
  finally: ...
except: ...
finally: ...