Java: Don't offer "Unwrap 'else' branch" intention if it might cause unreachable code (IDEA-165428)

java/java-tests/testData/codeInsight/unwrapElseBranch/beforeBlock2.java

@@ -0,0 +1,13 @@
+// "Unwrap 'else' branch (changes semantics)" "true"
+
+class T {
+    void f(boolean b) {
+        if (b) {
+            System.out.println("When true");
+        } <caret>else {
+            // Before
+            System.out.println("Otherwise");
+            // After
+        }
+    }
+}