JS: Make PropWrite not depend on SourceNode

Author: asgerf

javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll

@@ -647,25 +647,24 @@ module DataFlow {
    * writes to the corresponding property.
    */
   private class ObjectDefinePropertyAsPropWrite extends PropWrite, ValueNode {
-    CallToObjectDefineProperty odp;
+    override MethodCallExpr astNode;
 
-    ObjectDefinePropertyAsPropWrite() { odp = this }
+    ObjectDefinePropertyAsPropWrite() {
+      astNode.getReceiver().(GlobalVarAccess).getName() = "Object" and
+      astNode.getMethodName() = "defineProperty"
+    }
 
-    override Node getBase() { result = odp.getBaseObject() }
+    override Node getBase() { result = astNode.getArgument(0).flow() }
 
-    override Expr getPropertyNameExpr() { result = odp.getArgument(1).asExpr() }
+    override Expr getPropertyNameExpr() { result = astNode.getArgument(1) }
 
-    override string getPropertyName() { result = odp.getPropertyName() }
+    override string getPropertyName() { result = astNode.getArgument(1).getStringValue() }
 
     override Node getRhs() {
-      // not using `CallToObjectDefineProperty::getAPropertyAttribute` for performance reasons
-      exists(ObjectLiteralNode propdesc |
-        propdesc.flowsTo(odp.getPropertyDescriptor()) and
-        propdesc.hasPropertyWrite("value", result)
-      )
+      result = astNode.getArgument(2).(ObjectExpr).getPropertyByName("value").getInit().flow()
     }
 
-    override ControlFlowNode getWriteNode() { result = odp.getAstNode() }
+    override ControlFlowNode getWriteNode() { result = astNode }
   }
 
   /**