[mips][wasm] Access "CEntryStub" from the root set.

Port 55643564 https://crrev.com/c/1714656

Original Commit Message:

    This removes a shortcut to a "CEntryStub" from the instance object and
    instead loads those values via the root set which is also referenced
    from the instance. It makes instance objects smaller.

Change-Id: I62d16960cb18e3cd69c2fa56da85a6bfc6064db4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1716473Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Yu Yin <xwafish@gmail.com>
Cr-Commit-Position: refs/heads/master@{#62907}

src/builtins/mips/builtins-mips.cc

@@ -2488,7 +2488,10 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
     __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ lw(a2, FieldMemOperand(kWasmInstanceRegister,
-                              WasmInstanceObject::kCEntryStubOffset));
+                              WasmInstanceObject::kIsolateRootOffset));
+    auto centry_id =
+        Builtins::kCEntry_Return1_DontSaveFPRegs_ArgvOnStack_NoBuiltinExit;
+    __ lw(a2, MemOperand(a2, IsolateData::builtin_slot_offset(centry_id)));
     // Initialize the JavaScript context with 0. CEntry will use it to
     // set the current context on the isolate.
     __ Move(kContextRegister, Smi::zero());

src/builtins/mips64/builtins-mips64.cc

@@ -2525,7 +2525,10 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
     __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ Ld(a2, FieldMemOperand(kWasmInstanceRegister,
-                              WasmInstanceObject::kCEntryStubOffset));
+                              WasmInstanceObject::kIsolateRootOffset));
+    auto centry_id =
+        Builtins::kCEntry_Return1_DontSaveFPRegs_ArgvOnStack_NoBuiltinExit;
+    __ Ld(a2, MemOperand(a2, IsolateData::builtin_slot_offset(centry_id)));
     // Initialize the JavaScript context with 0. CEntry will use it to
     // set the current context on the isolate.
     __ Move(kContextRegister, Smi::zero());