Strong-mode patches for //third_party/dart/intl

Required for Dart 1.17.0-dev.2.0 SDK roll.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=121894792
diff --git a/lib/src/intl/date_format_field.dart b/lib/src/intl/date_format_field.dart
index e8ac882..4c2905e 100644
--- a/lib/src/intl/date_format_field.dart
+++ b/lib/src/intl/date_format_field.dart
@@ -152,7 +152,7 @@
 
   /// Parse a month name, case-insensitively, and set it in [dateFields].
   /// Assumes that [input] is lower case.
-  void parseMonth(_Stream input, dateFields) {
+  void parseMonth(input, dateFields) {
     if (width <= 2) {
       handleNumericField(input, dateFields.setMonth);
       return;
diff --git a/lib/src/intl_message.dart b/lib/src/intl_message.dart
index ebc83d5..fea00fa 100644
--- a/lib/src/intl_message.dart
+++ b/lib/src/intl_message.dart
@@ -195,13 +195,13 @@
   /// and set their attributes by string names, so we override the indexing
   /// operators so that they behave like maps with respect to those attribute
   /// names.
-  operator [](x);
+  operator [](String x);
 
   /// When we create these from strings or from AST nodes, we want to look up
   /// and set their attributes by string names, so we override the indexing
   /// operators so that they behave like maps with respect to those attribute
   /// names.
-  operator []=(x, y);
+  operator []=(String x, y);
 
   List<String> get attributeNames;
 
@@ -410,7 +410,7 @@
 
   /// The AST node will have the attribute names as strings, so we translate
   /// between those and the fields of the class.
-  void operator []=(attributeName, value) {
+  void operator []=(String attributeName, value) {
     switch (attributeName) {
       case "desc":
         description = value;
@@ -438,7 +438,7 @@
 
   /// The AST node will have the attribute names as strings, so we translate
   /// between those and the fields of the class.
-  operator [](attributeName) {
+  operator [](String attributeName) {
     switch (attributeName) {
       case "desc":
         return description;
@@ -553,7 +553,7 @@
 
   /// The node will have the attribute names as strings, so we translate
   /// between those and the fields of the class.
-  void operator []=(attributeName, rawValue) {
+  void operator []=(String attributeName, rawValue) {
     var value = Message.from(rawValue, this);
     switch (attributeName) {
       case "female":
@@ -686,7 +686,7 @@
   get attributeNames => cases.keys;
   get codeAttributeNames => attributeNames;
 
-  void operator []=(attributeName, rawValue) {
+  void operator []=(String attributeName, rawValue) {
     var value = Message.from(rawValue, this);
     cases[attributeName] = value;
   }