In the asm.js code translated to wasm, we call imported functions via a
WASM_TO_JS stub, which first calls the function and then calls ToNumber
on the return value. Exceptions can happen in both calls.
We were only ever reporting the location of the function call, whereas
asm.js code executed via turbofan reported the location of the type
coercion operator ("+" on "+foo()" or "|" on "foo()|0").

This CL implements the same behaviour for asm.js code translated to
wasm. The following is changed:
- the AsmWasmBuilder records the parent node when descending on a binary
  operator (also "+foo()" is represented by a binary operation).
- it stores not one location per call in the source position side
  table, but two (one for the call, one for the parent which does the
  type coercion).
- the wasm compiler annotates the source positions "0" and "1" to the
  two calls in the WASM_TO_JS wrapper (only if the module origin is
  asm.js).
- during stack trace generation (in the StackTraceIterator), when we
  move from the WASM_TO_JS frame to the WASM frame, we remember at which
  call inside the WASM_TO_JS wrapper we are, and encode this information
  in the generated caller state, used for the WASM frame.
- the same information is also stored in the FrameArray which is used
  to reconstruct the stack trace later.

R=titzer@chromium.org, bradnelson@chromium.org
CC=jgruber@chromium.org
BUG=v8:4203,v8:5724

Review-Url: https://codereview.chromium.org/2555243002
Cr-Commit-Position: refs/heads/master@{#41599}