[wasm] Implement AST printing into an ostream

src/compiler/wasm-compiler.cc

Index: src/compiler/wasm-compiler.cc
diff --git a/src/compiler/wasm-compiler.cc b/src/compiler/wasm-compiler.cc
index 09290af06aa7023f3da35cb95f735427f4b24834..17ca611fc4a94804b63879fe58fcc2d88fea5d2e 100644
--- a/src/compiler/wasm-compiler.cc
+++ b/src/compiler/wasm-compiler.cc
@@ -3164,7 +3164,8 @@ SourcePositionTable* WasmCompilationUnit::BuildGraphForWasmFunction(
 
   int index = static_cast<int>(function_->func_index);
   if (index >= FLAG_trace_wasm_ast_start && index < FLAG_trace_wasm_ast_end) {
-    PrintAst(isolate_->allocator(), body);
+    OFStream os(stdout);
+    PrintAst(isolate_->allocator(), body, os);
   }
   if (FLAG_trace_wasm_decode_time) {
     *decode_ms = decode_timer.Elapsed().InMillisecondsF();