[NFC] SIL: Add ValueBase::isBeginApplyToken.

Forwards to the member function of the same name on
MultipleValueInstructionResult.

Author: nate-chandler

include/swift/SIL/SILValue.h

@@ -590,6 +590,8 @@ class ValueBase : public SILNode, public SILAllocated<ValueBase> {
 
   bool isGuaranteedForwarding() const;
 
+  bool isBeginApplyToken() const;
+
   /// Unsafely eliminate moveonly from this value's type. Returns true if the
   /// value's underlying type was move only and thus was changed. Returns false
   /// otherwise.

lib/SIL/IR/SILValue.cpp

@@ -191,6 +191,13 @@ bool ValueBase::isGuaranteedForwarding() const {
   return phi->isGuaranteedForwarding();
 }
 
+bool ValueBase::isBeginApplyToken() const {
+  auto *result = isaResultOf<BeginApplyInst>(this);
+  if (!result)
+    return false;
+  return result->isBeginApplyToken();
+}
+
 bool ValueBase::hasDebugTrace() const {
   for (auto *op : getUses()) {
     if (auto *debugValue = dyn_cast<DebugValueInst>(op->getUser())) {