Fix instrumentation test proguard parser when gmscore has annotations

Most output with annotations look like:
    Class member attributes (count = 2):
    - Deprecated attribute
    - Runtime visible annotations attribute:
      - Annotation [Ljava/lang/Deprecated;]:
  - Method:       <init>(Ljava/security/cert/X509Certificate;)V

But it was choking when it hit:
    Class member attributes (count = 2):
    - Runtime invisible annotations attribute:
      - Annotation [Landroid/support/annotation/Nullable;]:
    - Signature attribute:
      - Utf8 [()Ljava/util/List<Ljava/lang/String;>;]

The code was treating - Utf8 as an annotation-related line.

BUG=525035

Review URL: https://codereview.chromium.org/1869083002

Cr-Original-Commit-Position: refs/heads/master@{#386706}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 44a0b274c777c0a6aee6f5ba722c435e71d54273

android/pylib/utils/proguard.py

@@ -284,5 +284,8 @@ def Parse(proguard_output):
       if m:
         state.UpdateCurrentAnnotationFieldValue(
           m.group(2), _GetDepth(m.group(1)))
+      else:
+        state.InitMethod(None)
+
 
   return results