[Gin] Add V8IgnitionEager feature.

gin/v8_initializer.cc

Index: gin/v8_initializer.cc
diff --git a/gin/v8_initializer.cc b/gin/v8_initializer.cc
index c4d734dfc6a1ba09e2124be922934661be48a915..ad29d10effa846bd78a0c82ec04b37c7922f0ed9 100644
--- a/gin/v8_initializer.cc
+++ b/gin/v8_initializer.cc
@@ -440,13 +440,21 @@ void V8Initializer::Initialize(IsolateHolder::ScriptMode mode,
   if (base::FeatureList::IsEnabled(features::kV8Ignition)) {
     std::string flag("--ignition");
     v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));
-  }
 
-  if (base::FeatureList::IsEnabled(features::kV8IgnitionLazy)) {
-    std::string flag("--no-ignition-eager");
-    v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));
+    if (base::FeatureList::IsEnabled(features::kV8IgnitionEager)) {
+      std::string eager_flag("--ignition-eager");
+      v8::V8::SetFlagsFromString(
+          eager_flag.c_str(), static_cast<int>(eager_flag.size()));
+    }
+
+    if (base::FeatureList::IsEnabled(features::kV8IgnitionLazy)) {
+      std::string lazy_flag("--no-ignition-eager");
+      v8::V8::SetFlagsFromString(
+          lazy_flag.c_str(), static_cast<int>(lazy_flag.size()));
+    }
   }
 
+
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
   v8::StartupData natives;
   natives.data = reinterpret_cast<const char*>(g_mapped_natives->data());