Add --trace-hydrogen-filter flag.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 0460da1d089c6c79478bb6b64782a6dbfdc082fa..d82f33d7865774529ebe77d6fd3364cde27e3c38 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1258,9 +1258,11 @@ CompilationPhase::~CompilationPhase() {
 bool CompilationPhase::ShouldProduceTraceOutput() const {
   // Trace if the appropriate trace flag is set and the phase name's first
   // character is in the FLAG_trace_phase command line parameter.
-  bool tracing_on = info()->IsStub() ?
-      FLAG_trace_hydrogen_stubs :
-      FLAG_trace_hydrogen;
+  bool tracing_on = info()->IsStub()
+      ? FLAG_trace_hydrogen_stubs
+      : (FLAG_trace_hydrogen &&
+         info()->function()->debug_name()->PassesFilter(
+             FLAG_trace_hydrogen_filter));
   return (tracing_on &&
       OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }