MIPS: Fixed a bug in StringHelper::GenerateTwoCharacterSymbolTableProbe.

r9871 (5baeaf57) changed the fill value for deleted entries in hash tables from null_value to the_hole_value.
This commit changes an assertion in MIPS code that expects this value.

BUG=
TEST=

Review URL: http://codereview.chromium.org/8479028
Patch from Gergely Kis <gergely@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9955 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/code-stubs-mips.cc

@@ -5776,10 +5776,10 @@ void StringHelper::GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
     __ Branch(&is_string, ne, scratch, Operand(ODDBALL_TYPE));
 
     __ Branch(not_found, eq, undefined, Operand(candidate));
-    // Must be null (deleted entry).
+    // Must be the hole value (deleted entry).
     if (FLAG_debug_code) {
-      __ LoadRoot(scratch, Heap::kNullValueRootIndex);
-      __ Assert(eq, "oddball in symbol table is not undefined or null",
+      __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
+      __ Assert(eq, "oddball in symbol table is not undefined or the hole value",
           scratch, Operand(candidate));
     }
     __ jmp(&next_probe[i]);