You cannot use L3/L4 ACL options in L2 ACL's, and also EGRESS policing is not supported.

Here working example for you:

[edit interfaces ge-5/0/46 unit 0 family ethernet-switching]
       filter {
           input interface-police;
       }

[edit firewall]
    family ethernet-switching {
        filter interface-police {
            term limit-50m {
                then policer limit-50m;
            }
        }
    }

[edit firewall]
   policer limit-50m {
       filter-specific;
       if-exceeding {
           bandwidth-limit 50m;
           burst-size-limit 15k;
       }
       then discard;
   }

In this case policer will only limit INGRESS traffic. To limit also EGRESS traffic, another approach should be used. In order to shape INGRESS and EGRESS replace all above with:

[edit]
  class-of-service {
      interfaces {
          ge-5/0/46 {
              shaping-rate 50m;
          }
      }
  }

You cannot use L3/L4 ACL options in L2 ACL's, and also EGRESS policing is not supported.

Here working example for you:

[edit interfaces ge-5/0/46 unit 0 family ethernet-switching]
       filter {
           input interface-police;
       }

[edit firewall]
    family ethernet-switching {
        filter interface-police {
            term limit-50m {
                then policer limit-50m;
            }
        }
    }

[edit firewall]
   policer limit-50m {
       filter-specific;
       if-exceeding {
           bandwidth-limit 50m;
           burst-size-limit 15k;
       }
       then discard;
   }

In this case policer will only limit INGRESS traffic. To limit also EGRESS traffic add this section:

[edit]
  class-of-service {
      interfaces {
          ge-5/0/46 {
              shaping-rate 50m;
          }
      }
  }

Update

I was wrong. CoS applied only for interface output, so CoS shaping and input policing should be both applied.