[generators] Fix loading of FormalParameterCount on 64bit archs.

src/mips64/builtins-mips64.cc

Index: src/mips64/builtins-mips64.cc
diff --git a/src/mips64/builtins-mips64.cc b/src/mips64/builtins-mips64.cc
index 4a21519f9c66c757ee4cd912c1aa28169723fe2c..60f5b9874a4fc2b368f650724478260655cf4dde 100644
--- a/src/mips64/builtins-mips64.cc
+++ b/src/mips64/builtins-mips64.cc
@@ -763,7 +763,6 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
     __ ld(a0, FieldMemOperand(a4, JSFunction::kSharedFunctionInfoOffset));
     __ lw(a0,
          FieldMemOperand(a0, SharedFunctionInfo::kFormalParameterCountOffset));
-    __ SmiUntag(a0);
     // We abuse new.target both to indicate that this is a resume call and to
     // pass in the generator object.  In ordinary calls, new.target is always
     // undefined because generator functions are non-constructable.