Fix emitter crash from a goto inside a try-finally

Summary: If there was a goto inside the try block of a try-finally, with no other
region (such as a loop) around it, the emitter would crash. We didn't
need to check for m_parent's goto labels, because the loop header
already starts the search at the current region's parent.

Note that this still behaves incorrectly for a goto out of two nested
try-finally regions, e.g.:

```
try {
  try {
    goto bluh;
  } finally {
    // one
  }
} finally {
  // two
}
bluh:
...
```

In this case, `one` will get executed and then jump straight to `bluh`.
None of our active test cases test this yet (some of the zend/bad ones
do, though). I think this may require a deeper fix.

Reviewed By: @jdelong

Differential Revision: D1555786

hphp/compiler/analysis/emitter.cpp

@@ -1657,7 +1657,7 @@ void EmitterVisitor::emitGotoTrampoline(Emitter& e,
   for (region = region->m_parent.get(); true; region = region->m_parent.get()) {
     assert(region->m_gotoTargets.count(name));
     auto t = region->m_gotoTargets[name].target;
-    if (region->m_parent->m_gotoLabels.count(name)) {
+    if (region->m_gotoLabels.count(name)) {
       // If only there is the appropriate label inside the current region
       // perform a jump.
       Id stateLocal = getStateLocal();

hphp/test/slow/finally/goto-bare.php

@@ -0,0 +1,17 @@
+<?php
+
+function foo() {
+  try {
+    goto label;
+  } finally {
+    var_dump("finally1");
+  }
+
+  return "wrong!";
+
+label:
+  var_dump("label");
+  return "return2";
+}
+
+var_dump(foo());

hphp/test/slow/finally/goto-bare.php.expect

@@ -0,0 +1,3 @@
+string(8) "finally1"
+string(5) "label"
+string(7) "return2"