[wasm] Implement AST printing into an ostream

src/ostreams.h

 // Copyright 2014 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_OSTREAMS_H_
 #define V8_OSTREAMS_H_
 
 #include <cstddef>
 #include <cstdio>
 #include <cstring>
@@ skipping 48 matching lines @@
 struct AsReversiblyEscapedUC16 {
   explicit AsReversiblyEscapedUC16(uint16_t v) : value(v) {}
   uint16_t value;
 };
 
 struct AsEscapedUC16ForJSON {
   explicit AsEscapedUC16ForJSON(uint16_t v) : value(v) {}
   uint16_t value;
 };
 
+struct AsHex {
+  explicit AsHex(uint64_t v, uint8_t min_width = 0)
+      : value(v), min_width(min_width) {}
+  uint64_t value;
+  uint8_t min_width;
+};
 
 // Writes the given character to the output escaping everything outside of
 // printable/space ASCII range. Additionally escapes '\' making escaping
 // reversible.
 std::ostream& operator<<(std::ostream& os, const AsReversiblyEscapedUC16& c);
 
 // Same as AsReversiblyEscapedUC16 with additional escaping of \n, \r, " and '.
 std::ostream& operator<<(std::ostream& os, const AsEscapedUC16ForJSON& c);
 
 // Writes the given character to the output escaping everything outside
 // of printable ASCII range.
 std::ostream& operator<<(std::ostream& os, const AsUC16& c);
 
 // Writes the given character to the output escaping everything outside
 // of printable ASCII range.
 std::ostream& operator<<(std::ostream& os, const AsUC32& c);
 
+// Writes the given number to the output in hexadecimal notation.
+std::ostream& operator<<(std::ostream& os, const AsHex& v);
+
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OSTREAMS_H_