Revert "[ConstraintSystem] Add a way to get the elapsed time we've spent in a SolverScope."

This reverts commit 656952a.

Author: DougGregor

lib/Sema/CSSolver.cpp

@@ -484,9 +484,6 @@ ConstraintSystem::SolverScope::SolverScope(ConstraintSystem &cs)
   numDefaultedConstraints = cs.DefaultedConstraints.size();
   numCheckedConformances = cs.CheckedConformances.size();
   PreviousScore = cs.CurrentScore;
-  if (cs.Timer) {
-    startTime = cs.Timer->getElapsedProcessTimeInFractionalSeconds();
-  }
 
   cs.solverState->registerScope(this);
   assert(!cs.failedConstraint && "Unexpected failed constraint!");

lib/Sema/ConstraintSystem.h

@@ -1453,9 +1453,6 @@ class ConstraintSystem {
     /// The scope number of this scope. Set when the scope is registered.
     unsigned scopeNumber = 0;
 
-    /// Time in fractional seconds at which we entered this scope.
-    double startTime;
-
     /// Constraint graph scope associated with this solver scope.
     ConstraintGraphScope CGScope;
 
@@ -1467,13 +1464,6 @@ class ConstraintSystem {
   public:
     explicit SolverScope(ConstraintSystem &cs);
     ~SolverScope();
-
-    Optional<double> getElapsedTimeInFractionalSeconds() {
-      if (!cs.Timer)
-        return None;
-
-      return cs.Timer->getElapsedProcessTimeInFractionalSeconds() - startTime;
-    }
   };
 
   ConstraintSystem(TypeChecker &tc, DeclContext *dc,