[wasm] Add --trace-wasm-ast-start and --trace-wasm-ast-end options and improve tracing.

src/wasm/wasm-module.cc

 // Copyright 2015 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.
 
 #include "src/macro-assembler.h"
 #include "src/objects.h"
 #include "src/v8.h"
 
 #include "src/simulator.h"
 
@@ skipping 441 matching lines @@
       instance.import_code.push_back(code);
       index++;
     }
   }
 
   //-------------------------------------------------------------------------
   // Compile all functions in the module.
   //-------------------------------------------------------------------------
 
   // First pass: compile each function and initialize the code table.
-  index = 0;
-  for (const WasmFunction& func : functions) {
+  index = FLAG_skip_compiling_wasm_funcs;
+  while (index < functions.size()) {
+    const WasmFunction& func = functions[index];
     if (thrower.error()) break;
     DCHECK_EQ(index, func.func_index);
 
     WasmName str = GetName(func.name_offset, func.name_length);
     WasmName str_null = {nullptr, 0};
     Handle<String> name = factory->InternalizeUtf8String(
         Vector<const char>(str.name, str.length));
     Handle<Code> code = Handle<Code>::null();
     Handle<JSFunction> function = Handle<JSFunction>::null();
     if (func.external) {
@@ skipping 214 matching lines @@
   }
   if (result->IsHeapNumber()) {
     return static_cast<int32_t>(HeapNumber::cast(*result)->value());
   }
   thrower.Error("WASM.compileRun() failed: Return value should be number");
   return -1;
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8