VM: Improve unoptimized code size by avoid emitting field guards.

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
===================================================================
--- runtime/vm/intermediate_language_ia32.cc	(revision 45494)
+++ runtime/vm/intermediate_language_ia32.cc	(working copy)
@@ -1425,10 +1425,7 @@
   const intptr_t field_cid = field().guarded_cid();
   const intptr_t nullability = field().is_nullable() ? kNullCid : kIllegalCid;
 
-  if (field_cid == kDynamicCid) {
-    ASSERT(!compiler->is_optimizing());
-    return;  // Nothing to emit.
-  }
+  ASSERT(field_cid != kDynamicCid);
 
   const bool emit_full_guard =
       !compiler->is_optimizing() || (field_cid == kIllegalCid);
@@ -1580,10 +1577,7 @@
 
 
 void GuardFieldLengthInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  if (field().guarded_list_length() == Field::kNoFixedLength) {
-    ASSERT(!compiler->is_optimizing());
-    return;  // Nothing to emit.
-  }
+  ASSERT(field().guarded_list_length() != Field::kNoFixedLength);
 
   Label* deopt = compiler->is_optimizing() ?
       compiler->AddDeoptStub(deopt_id(), ICData::kDeoptGuardField) : NULL;