Remove extra !isRubyBignum guards, RubyDynamicObject cannot be RubyBignum

Author: eregon

src/main/java/org/truffleruby/core/numeric/FloatNodes.java

@@ -286,7 +286,7 @@ protected RubyArray divMod(double a, RubyBignum b) {
             return divModNode.execute(a, b.value);
         }
 
-        @Specialization(guards = "!isRubyBignum(b)")
+        @Specialization
         protected Object divModCoerced(double a, RubyDynamicObject b,
                 @Cached DispatchNode redoCoerced) {
             return redoCoerced.call(a, "redo_coerced", coreSymbols().DIVMOD, b);

src/main/java/org/truffleruby/language/objects/IsImmutableObjectNode.java

@@ -48,7 +48,7 @@ protected boolean isImmutableObject(ImmutableRubyObject object) {
         return true;
     }
 
-    @Specialization(guards = "!isRubyBignum(object)")
+    @Specialization
     protected boolean isImmutableObject(RubyDynamicObject object,
             @Cached LogicalClassNode logicalClassNode) {
         final RubyClass logicalClass = logicalClassNode.execute(object);