MIPS64: Use weak cell in LoadGlobal handler.

Port bc0d2e23

BUG=v8:3629
LOG=N
TBR=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/814193004

Cr-Commit-Position: refs/heads/master@{#25906}

src/ic/mips64/handler-compiler-mips64.cc

@@ -702,7 +702,8 @@ Handle<Code> NamedLoadHandlerCompiler::CompileLoadGlobal(
 
   // Get the value from the cell.
   Register result = StoreDescriptor::ValueRegister();
-  __ li(result, Operand(cell));
+  Handle<WeakCell> weak_cell = factory()->NewWeakCell(cell);
+  __ LoadWeakValue(result, weak_cell, &miss);
   __ ld(result, FieldMemOperand(result, Cell::kValueOffset));
 
   // Check for deleted property if property can actually be deleted.