[crankshaft] Remove dead Variable hole-checking code

src/bailout-reason.h

Index: src/bailout-reason.h
diff --git a/src/bailout-reason.h b/src/bailout-reason.h
index 23af63e42a4230d5dc08fecf40228cec0eb8c47d..d9e9215682115b9c079a3f6ca48394ddc98f6529 100644
--- a/src/bailout-reason.h
+++ b/src/bailout-reason.h
@@ -20,8 +20,6 @@ namespace internal {
   V(kArgumentsObjectValueInATestContext,                                       \
     "Arguments object value in a test context")                                \
   V(kArrayIndexConstantValueTooBig, "Array index constant value too big")      \
-  V(kAssignmentToLetVariableBeforeInitialization,                              \
-    "Assignment to let variable before initialization")                        \
   V(kAssignmentToLOOKUPVariable, "Assignment to LOOKUP variable")              \
   V(kAssignmentToParameterFunctionUsesArgumentsObject,                         \
     "Assignment to parameter, function uses arguments object")                 \
@@ -245,7 +243,6 @@ namespace internal {
     "Unexpected type for RegExp data, FixedArray expected")                    \
   V(kUnexpectedValue, "Unexpected value")                                      \
   V(kUnsupportedDoubleImmediate, "Unsupported double immediate")               \
-  V(kUnsupportedLetCompoundAssignment, "Unsupported let compound assignment")  \
   V(kUnsupportedLookupSlotInDeclaration,                                       \
     "Unsupported lookup slot in declaration")                                  \
   V(kUnsupportedModuleOperation, "Unsupported module operation")               \