[wasm] Implement {Compile,Runtime}Error; fix traps from start function

src/wasm/wasm-result.h

 // 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.
 
 #ifndef V8_WASM_RESULT_H_
 #define V8_WASM_RESULT_H_
 
 #include <memory>
 
 #include "src/base/compiler-specific.h"
@@ skipping 73 matching lines @@
 
 std::ostream& operator<<(std::ostream& os, const ErrorCode& error_code);
 
 // A helper for generating error messages that bubble up to JS exceptions.
 class V8_EXPORT_PRIVATE ErrorThrower {
  public:
   ErrorThrower(i::Isolate* isolate, const char* context)
       : isolate_(isolate), context_(context) {}
   ~ErrorThrower();
 
-  PRINTF_FORMAT(2, 3) void Error(const char* fmt, ...);
   PRINTF_FORMAT(2, 3) void TypeError(const char* fmt, ...);
   PRINTF_FORMAT(2, 3) void RangeError(const char* fmt, ...);
+  PRINTF_FORMAT(2, 3) void CompileError(const char* fmt, ...);
+  PRINTF_FORMAT(2, 3) void RuntimeError(const char* fmt, ...);
 
   template <typename T>
-  void Failed(const char* error, Result<T>& result) {
+  void CompileFailed(const char* error, Result<T>& result) {
     std::ostringstream str;
     str << error << result;
-    Error("%s", str.str().c_str());
+    CompileError("%s", str.str().c_str());
   }
 
   i::Handle<i::Object> Reify() {
     i::Handle<i::Object> result = exception_;
     exception_ = i::Handle<i::Object>::null();
     return result;
   }
 
   bool error() const { return !exception_.is_null(); }
 
  private:
   void Format(i::Handle<i::JSFunction> constructor, const char* fmt, va_list);
 
   i::Isolate* isolate_;
   const char* context_;
   i::Handle<i::Object> exception_;
 };
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif