JS: Disable variable capture heuristic

Bailing out can be more expensive as the resulting jump steps themselves
cause perf issues. The limit of 100 variables per scope has also been
added in the interim, which handles the cases that this needed to cover.

Author: asgerf

javascript/ql/lib/semmle/javascript/dataflow/internal/VariableCapture.qll

@@ -23,35 +23,11 @@ module VariableCaptureConfig implements InputSig<js::DbLocation> {
     or
     isTopLevelLike(container.(js::ImmediatelyInvokedFunctionExpr).getEnclosingContainer())
     or
-    // Functions declared in a top-level with no parameters and can't generate flow-through, except through 'this'
-    // which we rule out with a few syntactic checks. In this case we treat its captured variables as singletons.
-    // NOTE: This was done to prevent a blow-up in fiddlesalad where a function called 'Runtime' captures 7381 variables but is only called once.
-    exists(js::Function fun |
-      container = fun and
-      fun.getNumParameter() = 0 and
-      isTopLevelLike(fun.getEnclosingContainer()) and
-      not mayHaveFlowThroughThisArgument(fun)
-    )
-    or
-    // Container declaring >100 captured variables tend to be singletons and are too expensive anyway
+    // Containers declaring >100 captured variables tend to be singletons and are too expensive anyway
     strictcount(js::LocalVariable v | v.isCaptured() and v.getDeclaringContainer() = container) >
       100
   }
 
-  private predicate hasLocalConstructorCall(js::Function fun) {
-    fun = getLambdaFromVariable(any(js::NewExpr e).getCallee().(js::VarAccess).getVariable())
-  }
-
-  private predicate mayHaveFlowThroughThisArgument(js::Function fun) {
-    any(js::ThisExpr e).getBinder() = fun and
-    not hasLocalConstructorCall(fun) and // 'this' argument is assumed to be a fresh object
-    (
-      exists(fun.getAReturnedExpr())
-      or
-      exists(js::YieldExpr e | e.getContainer() = fun)
-    )
-  }
-
   class CapturedVariable extends LocalVariableOrThis {
     CapturedVariable() {
       DataFlowImplCommon::forceCachingInSameStage() and