Updates samples for latest beta release of the Flutter SDK (#492)

* Updating for beta release

* Re-adding pub get to Flutter travis script

jsonexample/pubspec.lock

@@ -15,13 +15,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.39.8"
-  archive:
-    dependency: transitive
-    description:
-      name: archive
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.13"
   args:
     dependency: transitive
     description:
@@ -35,7 +28,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.4.1"
+    version: "2.4.2"
   boolean_selector:
     dependency: transitive
     description:
@@ -106,6 +99,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "7.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
   charcode:
     dependency: transitive
     description:
@@ -120,6 +120,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.2"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.1"
   code_builder:
     dependency: transitive
     description:
@@ -133,7 +140,7 @@ packages:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.12"
+    version: "1.14.13"
   convert:
     dependency: transitive
     description:
@@ -162,6 +169,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.3.6"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   fixnum:
     dependency: transitive
     description:
@@ -214,13 +228,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "3.1.4"
-  image:
-    dependency: transitive
-    description:
-      name: image
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.1.12"
   io:
     dependency: transitive
     description:
@@ -262,7 +269,7 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.6"
+    version: "0.12.8"
   meta:
     dependency: transitive
     description:
@@ -304,7 +311,7 @@ packages:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.4"
+    version: "1.7.0"
   pedantic:
     dependency: "direct dev"
     description:
@@ -312,13 +319,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.9.0"
-  petitparser:
-    dependency: transitive
-    description:
-      name: petitparser
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.4.0"
   pool:
     dependency: transitive
     description:
@@ -386,7 +386,7 @@ packages:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.9.5"
   stream_channel:
     dependency: transitive
     description:
@@ -421,7 +421,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.15"
+    version: "0.2.17"
   timing:
     dependency: transitive
     description:
@@ -435,7 +435,7 @@ packages:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.2.0"
   vector_math:
     dependency: transitive
     description:
@@ -457,13 +457,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.0"
-  xml:
-    dependency: transitive
-    description:
-      name: xml
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "3.6.1"
   yaml:
     dependency: transitive
     description:
@@ -472,4 +465,4 @@ packages:
     source: hosted
     version: "2.2.1"
 sdks:
-  dart: ">=2.7.0 <3.0.0"
+  dart: ">=2.9.0-14.0.dev <3.0.0"