Remove support for Object.observe

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index c09eceeae7a6b60d475571908998f8f8545ba590..9728ef3596b94139353dae647ce74ce73735e24b 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -172,19 +172,6 @@ class CallSite {
   T(ObjectSetterExpectingFunction,                                             \
     "Object.prototype.__defineSetter__: Expecting function")                   \
   T(ObjectSetterCallable, "Setter must be a function: %")                      \
-  T(ObserveCallbackFrozen,                                                     \
-    "Object.observe cannot deliver to a frozen function object")               \
-  T(ObserveGlobalProxy, "% cannot be called on the global proxy object")       \
-  T(ObserveAccessChecked, "% cannot be called on access-checked objects")      \
-  T(ObserveInvalidAccept,                                                      \
-    "Third argument to Object.observe must be an array of strings.")           \
-  T(ObserveNonFunction, "Object.% cannot deliver to non-function")             \
-  T(ObserveNonObject, "Object.% cannot % non-object")                          \
-  T(ObserveNotifyNonNotifier, "notify called on non-notifier object")          \
-  T(ObservePerformNonFunction, "Cannot perform non-function")                  \
-  T(ObservePerformNonString, "Invalid non-string changeType")                  \
-  T(ObserveTypeNonString,                                                      \
-    "Invalid changeRecord with non-string 'type' property")                    \
   T(OrdinaryFunctionCalledAsConstructor,                                       \
     "Function object that's not a constructor was created with new")           \
   T(PromiseCyclic, "Chaining cycle detected for promise %")                    \