[Isolates] Move contents of Top into Isolate....

src/fast-codegen.cc

Index: src/fast-codegen.cc
===================================================================
--- src/fast-codegen.cc	(revision 4906)
+++ src/fast-codegen.cc	(working copy)
@@ -445,7 +445,7 @@
   FastCodeGenerator fast_cgen(&masm);
   fast_cgen.Generate(info);
   if (fast_cgen.HasStackOverflow()) {
-    ASSERT(!Top::has_pending_exception());
+    ASSERT(!Isolate::Current()->has_pending_exception());
     return Handle<Code>::null();
   }
 
@@ -456,7 +456,7 @@
   info->set_mode(CompilationInfo::SECONDARY);
   cgen.Generate(info);
   if (cgen.HasStackOverflow()) {
-    ASSERT(!Top::has_pending_exception());
+    ASSERT(!Isolate::Current()->has_pending_exception());
     return Handle<Code>::null();
   }