JS: Protect against bad join in BadRandomness

This code resulted in bad join orders in response to certain library
changes. The actual library changes have to be split into smaller pieces
but I'd like to ensure I don't run into the bad join again.

Author: asgerf

javascript/ql/src/Security/CWE-327/BadRandomness.ql

@@ -30,30 +30,26 @@ private int powerOfTwo() {
  * Gets a node that has value 2^n for some n.
  */
 private DataFlow::Node isPowerOfTwo() {
-  exists(DataFlow::Node prev |
-    prev.getIntValue() = powerOfTwo()
-    or
-    // Getting around the 32 bit ints in QL. These are some hex values of the form 0x10000000
-    prev.asExpr().(NumberLiteral).getValue() =
-      ["281474976710656", "17592186044416", "1099511627776", "68719476736", "4294967296"]
-  |
-    result = prev.getASuccessor*()
-  )
+  result.getIntValue() = powerOfTwo()
+  or
+  // Getting around the 32 bit ints in QL. These are some hex values of the form 0x10000000
+  result.asExpr().(NumberLiteral).getValue() =
+    ["281474976710656", "17592186044416", "1099511627776", "68719476736", "4294967296"]
+  or
+  result = isPowerOfTwo().getASuccessor()
 }
 
 /**
  * Gets a node that has value (2^n)-1 for some n.
  */
 private DataFlow::Node isPowerOfTwoMinusOne() {
-  exists(DataFlow::Node prev |
-    prev.getIntValue() = powerOfTwo() - 1
-    or
-    // Getting around the 32 bit ints in QL. These are some hex values of the form 0xfffffff
-    prev.asExpr().(NumberLiteral).getValue() =
-      ["281474976710655", "17592186044415", "1099511627775", "68719476735", "4294967295"]
-  |
-    result = prev.getASuccessor*()
-  )
+  result.getIntValue() = powerOfTwo() - 1
+  or
+  // Getting around the 32 bit ints in QL. These are some hex values of the form 0xfffffff
+  result.asExpr().(NumberLiteral).getValue() =
+    ["281474976710655", "17592186044415", "1099511627775", "68719476735", "4294967295"]
+  or
+  result = isPowerOfTwoMinusOne().getASuccessor()
 }
 
 /**