Ruby: update SQLite3 model

ruby/ql/lib/codeql/ruby/frameworks/Sqlite3.qll

@@ -15,21 +15,19 @@ private import codeql.ruby.Concepts
  * https://github.com/sparklemotion/sqlite3-ruby
  */
 module Sqlite3 {
+  private API::Node databaseConst() {
+    result = API::getTopLevelMember("SQLite3").getMember("Database")
+  }
+
+  private API::Node dbInstance() {
+    result = databaseConst().getInstance()
+    or
+    result = databaseConst().getMethod("new").getBlock().getParameter(0)
+  }
+
   /** Gets a method call with a receiver that is a database instance. */
   private DataFlow::CallNode getADatabaseMethodCall(string methodName) {
-    exists(API::Node dbInstance |
-      dbInstance = API::getTopLevelMember("SQLite3").getMember("Database").getInstance() and
-      (
-        result = dbInstance.getAMethodCall(methodName)
-        or
-        // e.g. SQLite3::Database.new("foo.db") |db| { db.some_method }
-        exists(DataFlow::BlockNode block |
-          result.getMethodName() = methodName and
-          block = dbInstance.getAValueReachableFromSource().(DataFlow::CallNode).getBlock() and
-          block.getParameter(0).flowsTo(result.getReceiver())
-        )
-      )
-    )
+    result = dbInstance().getAMethodCall(methodName)
   }
 
   /** A prepared but unexecuted SQL statement. */