Make maps in monomorphic IC stubs weak.

src/lithium-codegen.cc

Index: src/lithium-codegen.cc
diff --git a/src/lithium-codegen.cc b/src/lithium-codegen.cc
index 93ae3101a7779e50b21fe4e542334974bc75758e..189edeea6cdd9f9d98f8bc0fd7d4ac3a816d69d9 100644
--- a/src/lithium-codegen.cc
+++ b/src/lithium-codegen.cc
@@ -203,7 +203,7 @@ void LCodeGenBase::RegisterWeakObjectsInOptimizedCode(Handle<Code> code) {
   NoWeakObjectVerificationScope disable_verification_of_embedded_objects;
 #endif
   for (int i = 0; i < maps.length(); i++) {
-    maps.at(i)->AddDependentCode(DependentCode::kWeaklyEmbeddedGroup, code);
+    maps.at(i)->AddDependentCode(DependentCode::kWeakCodeGroup, code);
   }
   for (int i = 0; i < objects.length(); i++) {
     AddWeakObjectToCodeDependency(isolate()->heap(), objects.at(i), code);