Don't compute least upper bounds for expressions in statement positions inside blocks.

This may save huge amount of time (Fixes SI-5862) for complicated lubs. I had to remove the a check in adapt for
the part that transforms <expr> into { <expr>; () } when the expected type is Unit. The reason is in the
code.

As a side effect, we get more warnings for pure expressions in statement positions (see the change in the test file).

2 files changed, 3 insertions, 3 deletions

diff --git a/test/files/neg/checksensible.check b/test/files/neg/checksensible.check
index 23af94180a..772d58322d 100644
--- a/test/files/neg/checksensible.check
+++ b/test/files/neg/checksensible.check
@@ -77,8 +77,8 @@ checksensible.scala:63: error: comparing a fresh object using `!=' will always y
   new Exception() != new Exception()

                   ^

 checksensible.scala:66: error: comparing values of types Int and Null using `==' will always yield false

-  if (foo.length == null) "plante" else "plante pas"

-                 ^

+  val dummy = if (foo.length == null) "plante" else "plante pas"

+                             ^

 checksensible.scala:71: error: comparing values of types Bip and Bop using `==' will always yield false

   (x1 == x2)

       ^

diff --git a/test/files/neg/checksensible.scala b/test/files/neg/checksensible.scala
index 27ee908153..15a9b6d9b6 100644
--- a/test/files/neg/checksensible.scala
+++ b/test/files/neg/checksensible.scala
@@ -63,7 +63,7 @@ class EqEqRefTest {
   new Exception() != new Exception()
 
   val foo: Array[String] = Array("1","2","3")
-  if (foo.length == null) "plante" else "plante pas"
+  val dummy = if (foo.length == null) "plante" else "plante pas"
 
   // final classes with default equals
   val x1 = new Bip