Split TemplateHashMapImpl::Lookup into two methods

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index 90dde1541ee9b30d57ad0268256dbb8acd56b299..1d73c0e1c26bd1489d137d98fee4bf29513ee5a2 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -58,18 +58,14 @@ class CounterMap {
  public:
   CounterMap(): hash_map_(Match) { }
   Counter* Lookup(const char* name) {
-    i::HashMap::Entry* answer = hash_map_.Lookup(
-        const_cast<char*>(name),
-        Hash(name),
-        false);
+    i::HashMap::Entry* answer =
+        hash_map_.Lookup(const_cast<char*>(name), Hash(name));
     if (!answer) return NULL;
     return reinterpret_cast<Counter*>(answer->value);
   }
   void Set(const char* name, Counter* value) {
-    i::HashMap::Entry* answer = hash_map_.Lookup(
-        const_cast<char*>(name),
-        Hash(name),
-        true);
+    i::HashMap::Entry* answer =
+        hash_map_.LookupOrInsert(const_cast<char*>(name), Hash(name));
     DCHECK(answer != NULL);
     answer->value = value;
   }