MIPS: Cache IC handlers on the prototype's map if possible.

src/mips/stub-cache-mips.cc

Index: src/mips/stub-cache-mips.cc
diff --git a/src/mips/stub-cache-mips.cc b/src/mips/stub-cache-mips.cc
index 7fada5424b559f2fab6b72552e27fdf5dcfc6e41..5b66a7e9ac7823ad8395929256f7f0d8bb896ea3 100644
--- a/src/mips/stub-cache-mips.cc
+++ b/src/mips/stub-cache-mips.cc
@@ -885,12 +885,15 @@ Register StubCompiler::CheckPrototypes(Handle<HeapType> type,
 
       reg = holder_reg;  // From now on the object will be in holder_reg.
 
-      if (heap()->InNewSpace(*prototype)) {
-        // The prototype is in new space; we cannot store a reference to it
-        // in the code.  Load it from the map.
+      // Two possible reasons for loading the prototype from the map:
+      // (1) Can't store references to new space in code.
+      // (2) Handler is shared for all receivers with the same prototype
+      //     map (but not necessarily the same prototype instance).
+      bool load_prototype_from_map =
+          heap()->InNewSpace(*prototype) || depth == 1;
+      if (load_prototype_from_map) {
         __ lw(reg, FieldMemOperand(map_reg, Map::kPrototypeOffset));
       } else {
-        // The prototype is in old space; load it directly.
         __ li(reg, Operand(prototype));
       }
     }