Fix all strong mode errors and warnings.

lib/src/property.dart

Index: lib/src/property.dart
diff --git a/lib/src/property.dart b/lib/src/property.dart
index c2cf776af4df944f7046d21851b477935132fc4a..b4beaee8db92d0128010e97eac9db2c499c471ea 100644
--- a/lib/src/property.dart
+++ b/lib/src/property.dart
@@ -1232,4 +1232,4 @@ class BoxEdge {
   num get height => (top != null ? top : 0) + (bottom != null ? bottom : 0);
 }
 
-_mergeVal(x, y) => y != null ? y : x;
+/*=T*/ _mergeVal/*<T>*/(/*=T*/ x, /*=T*/ y) => y != null ? y : x;

[terry, 2016/04/14 21:16:43]

grep/regex ?

[Bob Nystrom, 2016/04/21 00:06:59]

Heh, nope. This is the actual current comment-based generic method syntax. With
the real syntax, this will become:

T _mergeVal<T>(T x, T y) => y != null ? y : x;

But the VM and dart2js don't support that yet.