Enable SSA by default for IA32 as well.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
===================================================================
--- runtime/vm/compiler.cc	(revision 10522)
+++ runtime/vm/compiler.cc	(working copy)
@@ -33,11 +33,7 @@
 DEFINE_FLAG(bool, disassemble_optimized, false, "Disassemble optimized code.");
 DEFINE_FLAG(bool, trace_bailout, false, "Print bailout from ssa compiler.");
 DEFINE_FLAG(bool, trace_compiler, false, "Trace compiler operations.");
-#if defined(TARGET_ARCH_X64)
 DEFINE_FLAG(bool, use_ssa, true, "Use SSA form");
-#else
-DEFINE_FLAG(bool, use_ssa, false, "Use SSA form");
-#endif
 DEFINE_FLAG(int, deoptimization_counter_threshold, 5,
     "How many times we allow deoptimization before we disallow"
     " certain optimizations");