JS: Fix query regressions from parenthesized expression removal

- WhitespaceContradictsPrecedence: suppress false positives where
  parenthesized inner expressions explicitly clarify precedence
- ExprHasNoEffect: continue flagging parenthesized anonymous function
  expressions as useless (they are valid code, not syntax errors)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: asgerf

javascript/ql/lib/Expressions/ExprHasNoEffect.qll

@@ -172,7 +172,8 @@ predicate hasNoEffect(Expr e) {
   // from a syntax error we already flag
   not exists(FunctionExpr fe, ExprStmt es | fe = e |
     fe = es.getExpr() and
-    not exists(fe.getName())
+    not exists(fe.getName()) and
+    not fe.isParenthesized()
   ) and
   // exclude block-level flow type annotations. For example: `(name: empty)`.
   not (

javascript/ql/src/Expressions/WhitespaceContradictsPrecedence.ql

@@ -81,6 +81,7 @@ predicate interestingNesting(BinaryExpr inner, BinaryExpr outer) {
   inner = outer.getAChildExpr() and
   not inner instanceof AssocNestedExpr and
   not inner instanceof HarmlessNestedExpr and
+  not inner.isParenthesized() and
   not benignWhitespace(outer)
 }
 

javascript/ql/test/query-tests/Expressions/ExprHasNoEffect/ExprHasNoEffect.expected

@@ -13,3 +13,4 @@
 | tst.js:61:2:61:20 | o.trivialNonGetter1 | This expression has no effect. |
 | tst.js:77:24:77:24 | o | This expression has no effect. |
 | uselessfn.js:1:2:1:26 | functio ... d.");\\n} | This expression has no effect. |
+| uselessfn.js:6:3:6:25 | functio ... d.");\\n} | This expression has no effect. |

javascript/ql/test/query-tests/Expressions/ExprHasNoEffect/uselessfn.js

@@ -1,3 +1,8 @@
 (function f() { // $ Alert
   console.log("I'm never called.");
 })
+
+// anonymous function in parens - valid code but useless
+;(function() { // $ Alert
+  console.log("Also never called.");
+})

javascript/ql/test/query-tests/Expressions/WhitespaceContradictsPrecedence/tst.js

@@ -52,3 +52,16 @@ x +   x >> 1
 
 // OK - asm.js-like
 x = x - 1|0;
+
+// OK - parenthesized inner expression clarifies precedence
+function ok_paren1(x) {
+	return (x + x)>>1;
+}
+
+function ok_paren2(o, p) {
+	return (p in o)&&o[p];
+}
+
+function ok_paren3(x) {
+	return (x  +  x) >> 1;
+}