more regression tests

testcases/regression/invalid/IfExpr1.scala

+object IfExpr1 {
+
+  def foo(): Int = {
+    var a = 1
+    var b = 2
+    if({a = a + 1; a != b})
+      a = a + 3
+    else
+      b = a + b
+    a
+  } ensuring(_ == 3)
+
+}

testcases/regression/invalid/IfExpr2.scala

+object IfExpr2 {
+
+  def foo(): Int = {
+    var a = 1
+    var b = 2
+    if(a < b) {
+      a = a + 3
+      b = b + 2
+      a = a + b
+    }
+    a
+  } ensuring(_ == 0)
+
+}

testcases/regression/valid/IfExpr2.scala

+object IfExpr2 {
+
+  def foo(): Int = {
+    var a = 1
+    var b = 2
+    if(a < b) {
+      a = a + 3
+      b = b + 2
+      a = a + b
+    }
+    a
+  } ensuring(_ == 8)
+
+}