Extract asString()

Before: 9874, 8736, 9694, 12634, 9970
After:  9802, 8736, 9630, 12588, 9910
Target: 9800, 8458, 9634, 12290, 9702

Author: bblanchon

src/ArduinoJson/Object/ObjectImpl.hpp

@@ -34,7 +34,8 @@ inline ObjectImpl::iterator ObjectImpl::findKey(TAdaptedString key) const {
   bool isKey = true;
   for (auto it = createIterator(); !it.done(); it.next(resources_)) {
     VariantImpl variant(it.data(), resources_);
-    if (isKey && stringEquals(key, adaptString(variant.asString())))
+    if (isKey && stringEquals(key, adaptString(VariantImpl::asString(
+                                       it.data(), resources_))))
       return it;
     isKey = !isKey;
   }

src/ArduinoJson/Variant/VariantData.hpp

@@ -316,7 +316,16 @@ class VariantImpl {
   }
 
   JsonString asString() const {
-    switch (type()) {
+    if (!data_)
+      return JsonString();
+    return asString(data_, resources_);
+  }
+
+  static JsonString asString(VariantData* data_, ResourceManager* resources_) {
+    ARDUINOJSON_ASSERT(data_ != nullptr);
+    ARDUINOJSON_ASSERT(resources_ != nullptr);
+
+    switch (data_->type) {
       case VariantType::TinyString:
         return JsonString(data_->content.asTinyString);
       case VariantType::LongString: