Remove strong mode support from Scope and Variable

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index 5d0e8cf63faee537a5676f77757292ebc7285fd9..41d7b281f7cffc6d55db67330780eaaf84145f67 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -334,8 +334,6 @@ class CallSite {
   T(StrongSuperCallMissing,                                                    \
     "In strong mode, invoking the super constructor in a subclass is "         \
     "required")                                                                \
-  T(StrongUnboundGlobal,                                                       \
-    "In strong mode, using an undeclared global variable '%' is not allowed")  \
   T(UnsupportedSuper, "Unsupported reference to 'super'")                      \
   /* RangeError */                                                             \
   T(DateRange, "Provided date is not in valid range.")                         \
@@ -487,8 +485,6 @@ class CallSite {
     "with 'break', 'continue', 'return' or 'throw'")                           \
   T(StrongUndefined,                                                           \
     "In strong mode, binding or assigning to 'undefined' is deprecated")       \
-  T(StrongUseBeforeDeclaration,                                                \
-    "In strong mode, declaring variable '%' before its use is required")       \
   T(StrongVar,                                                                 \
     "In strong mode, 'var' is deprecated, use 'let' or 'const' instead")       \
   T(TemplateOctalLiteral,                                                      \