Avoid (some) symbol lookups at parse time if preparse data is available.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 47105573fda7f763ff1abc0f31d98887703272f5..0d01fcc75e2a9e14c506acb82533027e956b1534 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1136,13 +1136,18 @@ ScriptData* ScriptData::PreCompile(v8::Handle<String> source) {
 ScriptData* ScriptData::New(const char* data, int length) {
   // Return an empty ScriptData if the length is obviously invalid.
   if (length % sizeof(unsigned) != 0) {
-    return new i::ScriptDataImpl(i::Vector<unsigned>());
+    return new i::ScriptDataImpl();
   }
 
   // Copy the data to ensure it is properly aligned.
   int deserialized_data_length = length / sizeof(unsigned);
+  // If aligned, don't create a copy of the data.
+  if (reinterpret_cast<intptr_t>(data) % sizeof(unsigned) == 0) {
+    return new i::ScriptDataImpl(data, length);
+  }
+  // Copy the data to align it.
   unsigned* deserialized_data = i::NewArray<unsigned>(deserialized_data_length);
-  memcpy(deserialized_data, data, length);
+  i::MemCopy(deserialized_data, data, length);
 
   return new i::ScriptDataImpl(
       i::Vector<unsigned>(deserialized_data, deserialized_data_length));