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

java/java-tests/testData/codeInsight/unwrapElseBranch/beforeBlock3.java

@@ -0,0 +1,11 @@
+// "Unwrap 'else' branch" "true"
+
+class T {
+    void f(boolean b) {
+        if (b)
+            throw new RuntimeException("When true");
+        <caret>else {
+            System.out.println("Otherwise");
+        }
+    }
+}