Stack maps: Refactor constructors.

Create dedicated static methods instead of passing flags.
This creates dedicated methods for the purpose and merges
constructor and decoding into single optimized method.

This speeds up CodeInfo by 10%, and maps startup by 0.1%.

Test: ./art/test.py -b --host
Change-Id: Ic7d43e22bca0be9fb13bc2c7544ebfdf46798cfe
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 172fe3e..3fc6fd1 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -82,7 +82,7 @@
   DCHECK(!(*cur_quick_frame_)->IsNative());
   const OatQuickMethodHeader* header = GetCurrentOatQuickMethodHeader();
   if (cur_inline_info_.first != header) {
-    cur_inline_info_ = std::make_pair(header, CodeInfo(header, CodeInfo::InlineInfoOnly));
+    cur_inline_info_ = std::make_pair(header, CodeInfo::DecodeInlineInfoOnly(header));
   }
   return &cur_inline_info_.second;
 }