Change File.directory to not do any IO

runtime/bin/file.h

Index: runtime/bin/file.h
diff --git a/runtime/bin/file.h b/runtime/bin/file.h
index cfc48c150f892c018de2a2c996686222eb94eb77..839c5571eac1f008f37d5c914562f91066c7d065 100644
--- a/runtime/bin/file.h
+++ b/runtime/bin/file.h
@@ -67,26 +67,25 @@ class File {
     kDeleteRequest = 2,
     kOpenRequest = 3,
     kFullPathRequest = 4,
-    kDirectoryRequest = 5,
-    kCloseRequest = 6,
-    kPositionRequest = 7,
-    kSetPositionRequest = 8,
-    kTruncateRequest = 9,
-    kLengthRequest = 10,
-    kLengthFromPathRequest = 11,
-    kLastModifiedRequest = 12,
-    kFlushRequest = 13,
-    kReadByteRequest = 14,
-    kWriteByteRequest = 15,
-    kReadRequest = 16,
-    kReadIntoRequest = 17,
-    kWriteFromRequest = 18,
-    kCreateLinkRequest = 19,
-    kDeleteLinkRequest = 20,
-    kLinkTargetRequest = 21,
-    kTypeRequest = 22,
-    kIdenticalRequest = 23,
-    kStatRequest = 24
+    kCloseRequest = 5,
+    kPositionRequest = 6,
+    kSetPositionRequest = 7,
+    kTruncateRequest = 8,
+    kLengthRequest = 9,
+    kLengthFromPathRequest = 10,
+    kLastModifiedRequest = 11,
+    kFlushRequest = 12,
+    kReadByteRequest = 13,
+    kWriteByteRequest = 14,
+    kReadRequest = 15,
+    kReadIntoRequest = 16,
+    kWriteFromRequest = 17,
+    kCreateLinkRequest = 18,
+    kDeleteLinkRequest = 19,
+    kLinkTargetRequest = 20,
+    kTypeRequest = 21,
+    kIdenticalRequest = 22,
+    kStatRequest = 23
   };
 
   enum FileStat {
@@ -159,7 +158,6 @@ class File {
   static char* LinkTarget(const char* pathname);
   static bool IsAbsolutePath(const char* path);
   static char* GetCanonicalPath(const char* path);
-  static char* GetContainingDirectory(char* path);
   static const char* PathSeparator();
   static const char* StringEscapedPathSeparator();
   static Type GetType(const char* path, bool follow_links);