Put HashMap class in dart namespace.

runtime/platform/hashmap.h

Index: runtime/platform/hashmap.h
diff --git a/runtime/platform/hashmap.h b/runtime/platform/hashmap.h
index 1b144d459dd604dc8cc6b11aae431cbaa0aa1f8d..01fad72157fe69ca23cbcaca1f05a273d6b30bbb 100644
--- a/runtime/platform/hashmap.h
+++ b/runtime/platform/hashmap.h
@@ -7,6 +7,8 @@
 
 #include "platform/globals.h"
 
+namespace dart {

[Ivan Posva, 2013/04/30 15:07:53]

We should NOT pollute the dart namespace from outside the VM code.

[tfarina, 2013/04/30 16:31:03]

What is your argument about leaving it in the global namespace? Did you run the
command line "git grep --files-without-match  "namespace dart"
runtime/platform/"?
Why would runtime/vm be special and only it use dart namespace? runtime/bin uses
dart::bin namespace already.

v8 on the other hand has all its implementation in src/ and the types are inside
v8::internal namespace, while the public api is in include/v8.h and in the v8
namespace.

Søren suggested that we would put this also in dart::platform namespace. Which
would be consistent with dart::bin namespace.

But that is mirror, and I wouldn't worry too much about this anyway.

+
 class HashMap {
  public:
   typedef bool (*MatchFun) (void* key1, void* key2);
@@ -73,4 +75,6 @@ class HashMap {
   friend class IntSet;  // From hashmap_test.cc
 };
 
+}  // namespace dart
+
 #endif  // PLATFORM_HASHMAP_H_