AAPT2: Fix source output when error occurs in style

We were serializing the wrong Source when writing to protobuf

Change-Id: Ib65e962ebc1244ddf4af0e5666aaaebe5f7864a8

tools/aapt2/proto/TableProtoSerializer.cpp

@@ -111,7 +111,7 @@ public:
             serializeReferenceToPb(entry.key, pbEntry->mutable_key());
 
             pb::Item* pbItem = pbEntry->mutable_item();
-            serializeItemCommonToPb(*entry.value, pbEntry);
+            serializeItemCommonToPb(entry.key, pbEntry);
             PbSerializerVisitor subVisitor(mSourcePool, mSymbolPool, pbItem);
             entry.value->accept(&subVisitor);
         }