Add type inference for assignment to local variables.

pkg/front_end/testcases/inference/infer_assign_to_local_upwards.dart.strong.expect

Index: pkg/front_end/testcases/inference/infer_assign_to_local_upwards.dart.strong.expect
diff --git a/pkg/front_end/testcases/inference/infer_assign_to_local_upwards.dart.strong.expect b/pkg/front_end/testcases/inference/infer_assign_to_local_upwards.dart.strong.expect
new file mode 100644
index 0000000000000000000000000000000000000000..24280edcd0e8f74f873a7d2c95cd6dad86ca82ce
--- /dev/null
+++ b/pkg/front_end/testcases/inference/infer_assign_to_local_upwards.dart.strong.expect
@@ -0,0 +1,45 @@
+library test;
+import self as self;
+import "dart:core" as core;
+
+static method getInt() → core::int
+  return 0;
+static method getNum() → core::num
+  return 0;
+static method getDouble() → core::double
+  return 0.0;
+static method test1(core::int t) → void {
+  core::int v1 = t = self::getInt();
+  core::num v2 = t = self::getNum();
+  core::int v4 = let final dynamic #t1 = t in #t1.{core::num::==}(null) ? t = self::getInt() : #t1;
+  core::num v5 = let final dynamic #t2 = t in #t2.{core::num::==}(null) ? t = self::getNum() : #t2;
+  core::int v7 = t = t.{core::num::+}(self::getInt());
+  core::num v8 = t = t.{core::num::+}(self::getNum());
+  core::int v10 = t = t.{core::num::+}(1);
+  core::int v11 = let final dynamic #t3 = t in let final dynamic #t4 = t = #t3.{core::num::+}(1) in #t3;
+}
+static method test2(core::num t) → void {
+  core::int v1 = t = self::getInt();
+  core::num v2 = t = self::getNum();
+  core::double v3 = t = self::getDouble();
+  core::num v4 = let final dynamic #t5 = t in #t5.{core::num::==}(null) ? t = self::getInt() : #t5;
+  core::num v5 = let final dynamic #t6 = t in #t6.{core::num::==}(null) ? t = self::getNum() : #t6;
+  core::num v6 = let final dynamic #t7 = t in #t7.{core::num::==}(null) ? t = self::getDouble() : #t7;
+  core::num v7 = t = t.{core::num::+}(self::getInt());
+  core::num v8 = t = t.{core::num::+}(self::getNum());
+  core::num v9 = t = t.{core::num::+}(self::getDouble());
+  core::num v10 = t = t.{core::num::+}(1);
+  core::num v11 = let final dynamic #t8 = t in let final dynamic #t9 = t = #t8.{core::num::+}(1) in #t8;
+}
+static method test3(core::double t) → void {
+  core::num v2 = t = self::getNum();
+  core::double v3 = t = self::getDouble();
+  core::num v5 = let final dynamic #t10 = t in #t10.{core::num::==}(null) ? t = self::getNum() : #t10;
+  core::double v6 = let final dynamic #t11 = t in #t11.{core::num::==}(null) ? t = self::getDouble() : #t11;
+  core::double v7 = t = t.{core::double::+}(self::getInt());
+  core::double v8 = t = t.{core::double::+}(self::getNum());
+  core::double v9 = t = t.{core::double::+}(self::getDouble());
+  core::double v10 = t = t.{core::double::+}(1);
+  core::double v11 = let final dynamic #t12 = t in let final dynamic #t13 = t = #t12.{core::double::+}(1) in #t12;
+}
+static method main() → dynamic {}