PS: Add helper predicates for if statements.

powershell/ql/lib/semmle/code/powershell/ast/internal/If.qll

@@ -53,5 +53,13 @@ class If extends Expr, TIf {
     )
   }
 
+  StmtBlock getABranch(boolean b) {
+    b = true and result = this.getAThen()
+    or
+    b = false and result = this.getElse()
+  }
+
+  StmtBlock getABranch() { result = this.getAThen() or result = this.getElse() }
+
   predicate hasElse() { exists(this.getElse()) }
 }

powershell/ql/lib/semmle/code/powershell/controlflow/CfgNodes.qll

@@ -900,6 +900,16 @@ module ExprNodes {
     StmtCfgNode getAThen() { result = this.getThen(_) }
 
     StmtCfgNode getElse() { e.hasCfgChild(e.getElse(), this, result) }
+
+    StmtCfgNode getABranch(boolean b) {
+      b = true and
+      result = this.getAThen()
+      or
+      b = false and
+      result = this.getElse()
+    }
+
+    StmtCfgNode getABranch() { result = this.getABranch(_) }
   }
 
   private class LiteralChildMapping extends ExprChildMapping, Literal {