Implements a new API to set a function entry hook for profiling.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 5225763a3868219684ec8f454d39c0ab17fc7785..9843cd569a85fe92676b3992e57f2c74954d98b0 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -142,6 +142,11 @@ bool LCodeGen::GeneratePrologue() {
   }
 #endif
 
+  uintptr_t entry_hook = V8::GetFunctionEntryHook();
+  if (entry_hook != 0) {
+    __ call(reinterpret_cast<byte*>(entry_hook), RelocInfo::RUNTIME_ENTRY);
+  }
+
   // Strict mode functions and builtins need to replace the receiver
   // with undefined when called as functions (without an explicit
   // receiver object). ecx is zero for method calls and non-zero for