[wasm] Implement official wasm text format

src/wasm/s-expr.h

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_WASM_S_EXPR_H_
+#define V8_WASM_S_EXPR_H_
+
+#include <cstdint>
+#include <ostream>
+#include <tuple>
+#include <vector>
+
+namespace v8 {
+namespace internal {
+
+// Forward declaration.
+class AccountingAllocator;

[titzer, 2016/11/21 14:57:26]

Is this declaration necessary?

[Clemens Hammacher, 2016/11/21 17:48:40]

Nope, removed it.

+
+namespace wasm {
+
+// Forward declaration.
+struct WasmModule;
+
+// Generate s-expression disassembly.
+// Output disassembly to the given output stream, and optionally return an
+// offset table of <byte offset, line, column> via the given pointer.
+void PrintSExpr(const WasmModule *module, uint32_t func_index, std::ostream &os,
+                std::vector<std::tuple<uint32_t, int, int>> *offset_table);
+
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_WASM_S_EXPR_H_