accounts/abi: add support for "anonymous" and "indexed" for events (#3464)

accounts/abi/event.go

@@ -25,10 +25,12 @@ import (
 )
 
 // Event is an event potentially triggered by the EVM's LOG mechanism. The Event
-// holds type information (inputs) about the yielded output
+// holds type information (inputs) about the yielded output. Anonymous events
+// don't get the signature canonical representation as the first LOG topic.
 type Event struct {
-	Name   string
-	Inputs []Argument
+	Name      string
+	Anonymous bool
+	Inputs    []Argument
 }
 
 // Id returns the canonical representation of the event's signature used by the