[EH] Handle nested pops after inlining

[aheejin]

Inlining creates additional blocks at inlined call sites, which can be
inside a catch. For example:

(try
  (do)
  (catch $tag
    (call $callee
      (pop i32)
    )
  )
)

After inlining, this becomes

(try
  (do)
  (catch $tag
    (block $__inlined_func$callee
      (local.set $0
        (pop i32) ;; Invalid!!
      )
    (nop)
    )
  )
)

Now the pop is nested in a block, which makes this invalid. This PR
runs EHUtils::handleBlockNestedPops at the end to assign the pop to
a local right after the catch, making the code valid again:

(try
  (do)
  (catch $tag
    (local.set $new ;; New local to store `pop` result
      (pop i32)
    )
    (block $__inlined_func$callee
      (local.set $0
        (local.get $new)
      )
    (nop)
    )
  )
)

[tlively]

LGTM!