Add regression tests for #1400 (#1536)

Fixes #1400.

Author: sjakobi

dhall/tests/format/issue1400-1A.dhall

@@ -0,0 +1,14 @@
+{ conversation =
+    [ { author = "robert", content = [] }
+    , { author = "robert", content = [] }
+    , { author =
+          "bob"
+      , content =
+          [ text
+              ''
+              any line going past the 80 characters boundary (e.g. this one is 82)
+              ''
+          ]
+      }
+    ]
+}

dhall/tests/format/issue1400-1B.dhall

@@ -0,0 +1,13 @@
+{ conversation =
+    [ { author = "robert", content = [] }
+    , { author = "robert", content = [] }
+    , { author = "bob"
+      , content =
+          [ text
+              ''
+              any line going past the 80 characters boundary (e.g. this one is 82)
+              ''
+          ]
+      }
+    ]
+}

dhall/tests/format/issue1400-2A.dhall

@@ -0,0 +1,14 @@
+let Tagged
+    : Type → Type
+    =   λ ( a
+          : Type
+          )
+      → { field :
+            Text
+        , nesting :
+              ./Nesting sha256:6284802edd41d5d725aa1ec7687e614e21ad1be7e14dd10996bfa9625105c335
+            ? ./Nesting
+        , contents : a
+        }
+
+in  Tagged

dhall/tests/format/issue1400-2B.dhall

@@ -0,0 +1,11 @@
+let Tagged
+    : Type → Type
+    =   λ(a : Type)
+      → { field : Text
+        , nesting :
+              ./Nesting sha256:6284802edd41d5d725aa1ec7687e614e21ad1be7e14dd10996bfa9625105c335
+            ? ./Nesting
+        , contents : a
+        }
+
+in  Tagged