This changes different locations to extract the reference to the wasm
object and the function index from the stack trace, and make it
available through all the APIs which process stack traces.
The javascript CallSite object now has the new methods isWasm(),
getWasmObject() and getWasmFunctionIndex(); the byte offset is
available via getPosition().

Function names of wasm frames should be fully functional with this
commit, position information works reliably for calls, but not for
traps like unreachable or out-of-bounds accesses.

R=titzer@chromium.org, yangguo@chromium.org

Review-Url: https://codereview.chromium.org/1909353002
Cr-Commit-Position: refs/heads/master@{#36067}