Handle nested if statements with alternates in printer

[amasad]

Previously we saw a bug that when we have nested if statements
and an alternate then the generated code may confuse which
if statement the alternate belongs to.

e.g.

if (foo) if (bar) bar(); else baz();

But this was handled by looking at the consequent
and if it's an if we add a block. However we didn't
handle situations where it's not an if but the last
recursive statement is an if:

if (foo) while (bar) if (baz) baz(); else shoosh()

This handles it by recurring until we get the last
statement.

[codecov-io]

Current coverage is 85.02%

Merging #3180 into master will decrease coverage by -0.01% as of b72ad70

@@            master   #3180   diff @@
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  Files          215     215       
  Stmts        15628   15637     +9
  Branches      3338    3341     +3
  Methods          0       0       
======================================
+ Hit          13290   13295     +5
- Partial        683     687     +4
  Missed        1655    1655       

Review entire Coverage Diff as of b72ad70

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