When Crankshaft aborts compilation, use TurboFan next time

src/bailout-reason.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BAILOUT_REASON_H_
 #define V8_BAILOUT_REASON_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 230 matching lines @@
     "Unsupported const compound assignment")                                   \
   V(kUnsupportedCountOperationWithConst,                                       \
     "Unsupported count operation with const")                                  \
   V(kUnsupportedDoubleImmediate, "Unsupported double immediate")               \
   V(kUnsupportedLetCompoundAssignment, "Unsupported let compound assignment")  \
   V(kUnsupportedLookupSlotInDeclaration,                                       \
     "Unsupported lookup slot in declaration")                                  \
   V(kUnsupportedNonPrimitiveCompare, "Unsupported non-primitive compare")      \
   V(kUnsupportedPhiUseOfArguments, "Unsupported phi use of arguments")         \
   V(kUnsupportedPhiUseOfConstVariable,                                         \
-    "Unsupported phi use of const variable")                                   \
+    "Unsupported phi use of const or let variable")                            \
   V(kUnexpectedReturnFromBytecodeHandler,                                      \
     "Unexpectedly returned from a bytecode handler")                           \
   V(kUnexpectedReturnFromThrow, "Unexpectedly returned from a throw")          \
   V(kUnsupportedSwitchStatement, "Unsupported switch statement")               \
   V(kUnsupportedTaggedImmediate, "Unsupported tagged immediate")               \
   V(kVariableResolvedToWithContext, "Variable resolved to with context")       \
   V(kWeShouldNotHaveAnEmptyLexicalContext,                                     \
     "We should not have an empty lexical context")                             \
   V(kWithStatement, "WithStatement")                                           \
   V(kWrongFunctionContext, "Wrong context passed to function")                 \
   V(kWrongAddressOrValuePassedToRecordWrite,                                   \
     "Wrong address or value passed to RecordWrite")                            \
   V(kShouldNotDirectlyEnterOsrFunction,                                        \
     "Should not directly enter OSR-compiled function")                         \
   V(kYield, "Yield")
 
 #define ERROR_MESSAGES_CONSTANTS(C, T) C,
 enum BailoutReason {
   ERROR_MESSAGES_LIST(ERROR_MESSAGES_CONSTANTS) kLastErrorMessage
 };
 #undef ERROR_MESSAGES_CONSTANTS
 
 
 const char* GetBailoutReason(BailoutReason reason);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_BAILOUT_REASON_H_