Fix code review findings

Author: tamasvajk

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -837,7 +837,7 @@ private module Cached {
         )
         or
         // item = variable in node1 = (..., variable, ...) in a case/is var (..., ...)
-        exists(PatternExpr pe | pe.getAChild*() = te) and
+        te = any(PatternExpr pe).getAChildExpr*() and
         exists(AssignableDefinitions::LocalVariableDefinition lvd, Ssa::ExplicitDefinition def |
           node2.(SsaDefinitionNode).getDefinition() = def and
           def.getADefinition() = lvd and

csharp/ql/src/semmle/code/csharp/exprs/Expr.qll

@@ -1040,7 +1040,7 @@ class TupleExpr extends Expr, @tuple_expr {
   /** Holds if this expression is a tuple construction. */
   predicate isConstruction() {
     not this = getAnAssignOrForeachChild() and
-    not exists(PatternExpr pe | pe.getAChild*() = this)
+    not this = any(PatternExpr pe).getAChildExpr*()
   }
 
   override string getAPrimaryQlClass() { result = "TupleExpr" }