To bring V8 into line with the proposed design changes in:

 https://github.com/WebAssembly/design/pull/489

(This CL is forked from https://codereview.chromium.org/1634673002/.
That CL doesn't merge cleanly, and I can't update it.)

TBR=titzer@chromium.org
LOG=Y
BUG=chromium:575167

Review URL: https://codereview.chromium.org/1682443002

Cr-Commit-Position: refs/heads/master@{#33828}

To bring V8 into line with the proposed design changes in:

 https://github.com/WebAssembly/design/pull/489

R=ahaas@chromium.org,bradnelson@chromium.org
LOG=Y
BUG=chromium:575167
BUG=v8:4735

Review URL: https://codereview.chromium.org/1624323003

Cr-Commit-Position: refs/heads/master@{#33776}

This cleans up and simplifyies handling the bytes followin an opcode
with little helper structs that will be useful in the interpreter and
already have been in keeping OpcodeArity and OpcodeLength up to date
with the decoder.

R=bradnelson@chromium.org, ahaas@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1664883002

Cr-Commit-Position: refs/heads/master@{#33723}

R=ahaas@chromium.org,jfb@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1661713003

Cr-Commit-Position: refs/heads/master@{#33702}

R=ahaas@chromium.org,bradnelson@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1644023002

Cr-Commit-Position: refs/heads/master@{#33595}

R=ahaas@chromium.org, bradnelson@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1642043002

Cr-Commit-Position: refs/heads/master@{#33581}

This CL implements loop assignment analysis, a pass over a loop's body
to record local variables that are assigned. This pre-pass is similar
to that done on the JavaScript AST for the same reason: avoid introducing
too many phis at loop headers when building a graph.

R=bradnelson@chromium.org,ahaas@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1617723003

Cr-Commit-Position: refs/heads/master@{#33486}

Motivated by finding a bug in a larger module, this CL adds the ability
to dump out a byte-by-byte, nested view of the decoded AST. This
byte-by-byte output uses the opcode enum to make it readable, but is
suitable for pasting into a byte[] in C or JS and thus making a regression
test.

Also fix a bug; the case of running out of registers for indirect calls.

R=ahaas@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1616973004

Cr-Commit-Position: refs/heads/master@{#33442}

R=ahaas@chromium.org
LOG=Y
BUG=chromium:575861

Review URL: https://codereview.chromium.org/1573053003

Cr-Commit-Position: refs/heads/master@{#33213}

Fixing several signed/unsigned comparison warnings for wasm.
Fixing a use after free involving ostringsteam::str()

R=ahaas@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1533593004

Cr-Commit-Position: refs/heads/master@{#32946}

As discussed in person, this adds the code from v8-native-prototype into
V8 proper, guarded by GYP flags that do not build the code by default.
Passing wasm=on to 'make' or setting v8_wasm as a GYP flag activates
building of this code.

An additional header file is added to and exported from the compiler
directory, src/compiler/wasm-compiler.h. This exposes a limited interface
with opaque Node and Graph types to the decoder to build TF graphs, as
well as functions to compile WASM graphs.

The mjsunit tests added are blacklisted because they fail without the
WASM object exposed to JS, which is also disabled by the build config
option.

This corresponds closely to https://github.com/WebAssembly/v8-native-prototype/commit/5981e06ebc9b1e578831d03100f17ebb77970ee0, with some formatting fixes and moving some files into src/compiler.

R=mstarzinger@chromium.org, bradnelson@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1504713014

Cr-Commit-Position: refs/heads/master@{#32794}