JS: Fix 'is, is' and 'is is'.

javascript/ql/src/semmle/javascript/Expr.qll

@@ -115,7 +115,7 @@ class Expr extends @expr, ExprOrStmt, ExprOrType, AST::ValueNode {
   predicate isImpure() { any() }
 
   /**
-   * Holds if this expression is pure, that is, is its evaluation is guaranteed
+   * Holds if this expression is pure, that is, its evaluation is guaranteed
    * to be side-effect free.
    */
   predicate isPure() { not isImpure() }

javascript/ql/src/semmle/javascript/Stmt.qll

@@ -95,7 +95,7 @@ class ControlStmt extends TControlStmt, Stmt {
 }
 
 /**
- * A loop, that is, is a while loop, a do-while loop, a for loop, or a for-in loop.
+ * A loop, that is, a while loop, a do-while loop, a for loop, or a for-in loop.
  *
  * Examples:
  *

javascript/ql/src/semmle/javascript/security/dataflow/PrototypePollutionCustomizations.qll

@@ -14,7 +14,7 @@ module PrototypePollution {
    * Label for wrappers around tainted objects, that is, objects that are
    * not completely user-controlled, but contain a user-controlled object.
    *
-   * For example, `options` below is is a tainted wrapper, but is not itself
+   * For example, `options` below is a tainted wrapper, but is not itself
    * a tainted object:
    * ```
    * let options = {