Revert r15361 "Improved function entry hook coverage" because of ARM build error.

src/code-stubs.cc

Index: src/code-stubs.cc
diff --git a/src/code-stubs.cc b/src/code-stubs.cc
index 2d94ec978e098da76d89aedb2b41c48d1d5b2d5d..5bec7e05f913be19ef8526f76e86580b99041115 100644
--- a/src/code-stubs.cc
+++ b/src/code-stubs.cc
@@ -757,11 +757,24 @@ void StubFailureTrampolineStub::GenerateAheadOfTime(Isolate* isolate) {
 }
 
 
+FunctionEntryHook ProfileEntryHookStub::entry_hook_ = NULL;
+
+
 void ProfileEntryHookStub::EntryHookTrampoline(intptr_t function,
                                                intptr_t stack_pointer) {
-  FunctionEntryHook entry_hook = Isolate::Current()->function_entry_hook();
-  ASSERT(entry_hook != NULL);
-  entry_hook(function, stack_pointer);
+  if (entry_hook_ != NULL)
+    entry_hook_(function, stack_pointer);
+}
+
+
+bool ProfileEntryHookStub::SetFunctionEntryHook(FunctionEntryHook entry_hook) {
+  // We don't allow setting a new entry hook over one that's
+  // already active, as the hooks won't stack.
+  if (entry_hook != 0 && entry_hook_ != 0)
+    return false;
+
+  entry_hook_ = entry_hook;
+  return true;
 }