ART: Move dex structs into own header

Separating out the structs from DexFile allows them to be forward-
declared, which reduces the need to include the dex_file header.

Bug: 119869270
Test: m
Change-Id: I32dde5a632884bca7435cd584b4a81883de2e7b4
diff --git a/compiler/compiler.cc b/compiler/compiler.cc
index 646040f..54da446 100644
--- a/compiler/compiler.cc
+++ b/compiler/compiler.cc
@@ -21,6 +21,7 @@
 #include "base/macros.h"
 #include "base/utils.h"
 #include "dex/code_item_accessors-inl.h"
+#include "dex/dex_file.h"
 #include "driver/compiler_driver.h"
 #include "optimizing/optimizing_compiler.h"
 
@@ -39,7 +40,7 @@
   }
 }
 
-bool Compiler::IsPathologicalCase(const DexFile::CodeItem& code_item,
+bool Compiler::IsPathologicalCase(const dex::CodeItem& code_item,
                                   uint32_t method_idx,
                                   const DexFile& dex_file) {
   /*