[wasm] Draft version of C/C++ Wasm API

Imported from https://github.com/WebAssembly/wasm-c-api/ and
updated to work inside V8.
Tests will be added in an upcoming CL.

This is experimental; it is not yet recommended to rely on it.

Change-Id: I05914f4b63298bf7c848c4d4c8811f0f6eb882e3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1516478
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60910}

BUILD.gn

@@ -3664,6 +3664,27 @@ if (v8_monolithic) {
   }
 }
 
+v8_static_library("wee8") {
+  deps = [
+    ":v8_base",
+    ":v8_libbase",
+    ":v8_libplatform",
+    ":v8_libsampler",
+    ":v8_maybe_snapshot",
+    "//build/win:default_exe_manifest",
+  ]
+
+  # TODO: v8dll-main.cc equivalent for shared library builds
+
+  configs = [ ":internal_config" ]
+
+  sources = [
+    "src/wasm/c-api.cc",
+    "third_party/wasm-c-api/wasm.h",
+    "third_party/wasm-c-api/wasm.hh",
+  ]
+}
+
 ###############################################################################
 # Executables
 #

LICENSE

@@ -20,11 +20,13 @@ are:
     This code is copyrighted by Sun Microsystems Inc. and released
     under a 3-clause BSD license.
 
-  - Valgrind client API header, located at third_party/valgrind/valgrind.h
-    This is release under the BSD license.
+  - Valgrind client API header, located at src/third_party/valgrind/valgrind.h
+    This is released under the BSD license.
 
-  - antlr4 parser generator Cpp library located in third_party/antlr4
-    This is release under the BSD license.
+  - The Wasm C/C++ API headers, located at third_party/wasm-api/wasm.{h,hh}
+    This is released under the Apache license. The API's upstream prototype
+    implementation also formed the basis of V8's implementation in
+    src/wasm/c-api.cc.
 
 These libraries have their own licenses; we recommend you read them,
 as their terms may differ from the terms below.

src/wasm/DEPS

+specific_include_rules = {
+  "c-api\.cc": [
+    "+include/libplatform/libplatform.h",
+    "+third_party/wasm-api/wasm.h",
+    "+third_party/wasm-api/wasm.hh",
+  ],
+}

third_party/wasm-api/README.v8

+Name: Wasm C/C++ API
+Short Name: wasm-c-api
+URL: https://github.com/WebAssembly/wasm-c-api/
+Version: 0
+Revision: 5c742b048f7766a0c00be3a7af23fb71ba816026
+Date: 2019-03-18
+License: Apache 2.0
+License File: LICENSE
+Security Critical: yes
+
+Description:
+Provides a "black box" API for embedding a Wasm engine in C/C++ applications.
+
+Local modifications:
+None.
+This is only the contents of the "include/" directory of the upstream
+repository.