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

java/java-tests/testData/codeInsight/unwrapElseBranch/beforeNotLastReachable1.java

@@ -0,0 +1,14 @@
+// "Unwrap 'else' branch (changes semantics)" "false"
+
+class T {
+    void m(boolean b) {
+        if (b) {
+            System.out.println(1);
+        }
+        <caret>else {
+            System.out.println(2);
+            return;
+        }
+        System.out.println(3);
+    }
+}