VM: Cache instructions entry point in RawFunction/RawCode.

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index d8aa210ee19f7556ea84b02796fe5cf1222a46fd..ea543f496b06edd867fc4745d25972795f81e3dd 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -218,12 +218,11 @@ void ClosureCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   // R4: Arguments descriptor.
   // R0: Function.
   ASSERT(locs()->in(0).reg() == R0);
-  __ LoadFieldFromOffset(R2, R0, Function::instructions_offset());
+  __ LoadFieldFromOffset(R2, R0, Function::entry_point_offset());
 
   // R2: instructions.
   // R5: Smi 0 (no IC data; the lazy-compile stub expects a GC-safe value).
   __ LoadImmediate(R5, 0);
-  __ AddImmediate(R2, R2, Instructions::HeaderSize() - kHeapObjectTag);
   __ blr(R2);
   compiler->RecordSafepoint(locs());
   // Marks either the continuation point in unoptimized code or the