Revert "ART: dex2oat flag for HGraphVisualizer dump file"

Breaks compilation of tests.

This reverts commit 54953dfdcb3bb8896d8af2d20adef84fb740ce77.

Change-Id: I868b876c3130be61f1169c5fccdffc0368bee11e
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index eaecbb0..692d452 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -149,12 +149,11 @@
   // Enable C1visualizer output. Must be done in Init() because the compiler
   // driver is not fully initialized when passed to the compiler's constructor.
   CompilerDriver* driver = GetCompilerDriver();
-  const std::string cfg_file_name = driver->GetDumpCfgFileName();
-  if (!cfg_file_name.empty()) {
+  if (driver->GetDumpPasses()) {
     CHECK_EQ(driver->GetThreadCount(), 1U)
       << "Graph visualizer requires the compiler to run single-threaded. "
       << "Invoke the compiler with '-j1'.";
-    visualizer_output_.reset(new std::ofstream(cfg_file_name));
+    visualizer_output_.reset(new std::ofstream("art.cfg"));
   }
 }