Merge parts of #5140 first for easier code review of functional changes

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/deser/std/CollectionDeserializer.java

@@ -341,12 +341,10 @@ protected Collection<Object> _deserializeFromArray(JsonParser p, Deserialization
         // [databind#631]: Assign current value, to be accessible by custom serializers
         p.assignCurrentValue(result);
 
-        JsonDeserializer<Object> valueDes = _valueDeserializer;
         // Let's offline handling of values with Object Ids (simplifies code here)
-        if (valueDes.getObjectIdReader() != null) {
+        if (_valueDeserializer.getObjectIdReader() != null) {
             return _deserializeWithObjectId(p, ctxt, result);
         }
-        final TypeDeserializer typeDeser = _valueTypeDeserializer;
         JsonToken t;
         while ((t = p.nextToken()) != JsonToken.END_ARRAY) {
             try {
@@ -356,10 +354,10 @@ protected Collection<Object> _deserializeFromArray(JsonParser p, Deserialization
                         continue;
                     }
                     value = _nullProvider.getNullValue(ctxt);
-                } else if (typeDeser == null) {
-                    value = valueDes.deserialize(p, ctxt);
+                } else if (_valueTypeDeserializer == null) {
+                    value = _valueDeserializer.deserialize(p, ctxt);
                 } else {
-                    value = valueDes.deserializeWithType(p, ctxt, typeDeser);
+                    value = _valueDeserializer.deserializeWithType(p, ctxt, _valueTypeDeserializer);
                 }
                 if (value == null) {
                     _tryToAddNull(p, ctxt, result);
@@ -400,9 +398,6 @@ protected final Collection<Object> handleNonArray(JsonParser p, DeserializationC
         if (!canWrap) {
             return (Collection<Object>) ctxt.handleUnexpectedToken(_containerType, p);
         }
-        JsonDeserializer<Object> valueDes = _valueDeserializer;
-        final TypeDeserializer typeDeser = _valueTypeDeserializer;
-
         Object value;
 
         try {
@@ -412,11 +407,12 @@ protected final Collection<Object> handleNonArray(JsonParser p, DeserializationC
                     return result;
                 }
                 value = _nullProvider.getNullValue(ctxt);
-            } else if (typeDeser == null) {
-                value = valueDes.deserialize(p, ctxt);
+            } else if (_valueTypeDeserializer == null) {
+                value = _valueDeserializer.deserialize(p, ctxt);
             } else {
-                value = valueDes.deserializeWithType(p, ctxt, typeDeser);
+                value = _valueDeserializer.deserializeWithType(p, ctxt, _valueTypeDeserializer);
             }
+            // _skipNullValues is checked by _tryToAddNull.
             if (value == null) {
                 _tryToAddNull(p, ctxt, result);
                 return result;
@@ -444,8 +440,6 @@ protected Collection<Object> _deserializeWithObjectId(JsonParser p, Deserializat
         // [databind#631]: Assign current value, to be accessible by custom serializers
         p.assignCurrentValue(result);
 
-        final JsonDeserializer<Object> valueDes = _valueDeserializer;
-        final TypeDeserializer typeDeser = _valueTypeDeserializer;
         CollectionReferringAccumulator referringAccumulator =
                 new CollectionReferringAccumulator(_containerType.getContentType().getRawClass(), result);
 
@@ -458,10 +452,10 @@ protected Collection<Object> _deserializeWithObjectId(JsonParser p, Deserializat
                         continue;
                     }
                     value = _nullProvider.getNullValue(ctxt);
-                } else if (typeDeser == null) {
-                    value = valueDes.deserialize(p, ctxt);
+                } else if (_valueTypeDeserializer == null) {
+                    value = _valueDeserializer.deserialize(p, ctxt);
                 } else {
-                    value = valueDes.deserializeWithType(p, ctxt, typeDeser);
+                    value = _valueDeserializer.deserializeWithType(p, ctxt, _valueTypeDeserializer);
                 }
                 if (value == null && _skipNullValues) {
                     continue;