Enable native symbol resolving on Windows again

runtime/vm/native_symbol_win.cc

Index: runtime/vm/native_symbol_win.cc
diff --git a/runtime/vm/native_symbol_win.cc b/runtime/vm/native_symbol_win.cc
index 3b5dddf252fa77531e83f49b42223dd9e1e21787..fa57d56cd733a5461e0d450019e569a6f1ae5683 100644
--- a/runtime/vm/native_symbol_win.cc
+++ b/runtime/vm/native_symbol_win.cc
@@ -20,7 +20,6 @@ void NativeSymbolResolver::InitOnce() {
   ASSERT(running_ == false);
   lock_ = new Mutex();
   running_ = true;
-#if 0
   SymSetOptions(SYMOPT_UNDNAME | SYMOPT_DEFERRED_LOADS);
   HANDLE hProcess = GetCurrentProcess();
   if (!SymInitialize(hProcess, NULL, TRUE)) {
@@ -28,7 +27,6 @@ void NativeSymbolResolver::InitOnce() {
     printf("Failed to init NativeSymbolResolver (SymInitialize %d)\n", error);
     return;
   }
-#endif
 }
 
 
@@ -38,13 +36,11 @@ void NativeSymbolResolver::ShutdownOnce() {
     return;
   }
   running_ = false;
-#if 0
   HANDLE hProcess = GetCurrentProcess();
   if (!SymCleanup(hProcess)) {
     DWORD error = GetLastError();
     printf("Failed to shutdown NativeSymbolResolver (SymCleanup  %d)\n", error);
   }
-#endif
 }
 
 
@@ -60,7 +56,6 @@ char* NativeSymbolResolver::LookupSymbolName(uintptr_t pc, uintptr_t* start) {
   if (start != NULL) {
     *start = NULL;
   }
-#if 0
   memset(&buffer[0], 0, sizeof(buffer));
   HANDLE hProcess = GetCurrentProcess();
   DWORD64 address = static_cast<DWORD64>(pc);
@@ -72,8 +67,6 @@ char* NativeSymbolResolver::LookupSymbolName(uintptr_t pc, uintptr_t* start) {
     return NULL;
   }
   return strdup(pSymbol->Name);
-#endif
-  return NULL;
 }