ARM64: Avoid iterating through all unresolved branch infos when many are pending.

src/arm64/instructions-arm64.h

Index: src/arm64/instructions-arm64.h
diff --git a/src/arm64/instructions-arm64.h b/src/arm64/instructions-arm64.h
index de76b69b6b87120154041d5a7e250569900c4421..cfa63a345c81df784b592ae702fad1f8bf1a7c53 100644
--- a/src/arm64/instructions-arm64.h
+++ b/src/arm64/instructions-arm64.h
@@ -192,6 +192,10 @@ class Instruction {
     return Mask(TestBranchFMask) == TestBranchFixed;
   }
 
+  bool IsImmBranch() const {
+    return BranchType() != UnknownBranchType;
+  }
+
   bool IsLdrLiteral() const {
     return Mask(LoadLiteralFMask) == LoadLiteralFixed;
   }