Allowing optional build of a WASM prototype behind a gyp define.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 5ab05f6417346270e2c2b522de95599a6888f479..2b12e657898463c483daa1aa91639be36564a67f 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -446,6 +446,14 @@ DEFINE_BOOL(turbo_frame_elision, true, "elide frames in TurboFan")
 DEFINE_BOOL(turbo_cache_shared_code, true, "cache context-independent code")
 DEFINE_BOOL(turbo_preserve_shared_code, false, "keep context-independent code")
 
+#if defined(V8_WASM)
+// Flags for native WebAssembly.
+DEFINE_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
+DEFINE_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
+DEFINE_BOOL(wasm_break_on_decoder_error, false,
+            "debug break when wasm decoder encounters an error")
+#endif
+
 DEFINE_INT(typed_array_max_size_in_heap, 64,
            "threshold for in-heap typed array")