Add .zero directive

asm.js

@@ -106,6 +106,7 @@ const State = Object.freeze({
     ELEM_TABLE:   33,
     ELEM_ELEM:    34,
     ELEM_LABEL:   35,
+    ZERO:         36,
 });
 
 const Action = Object.freeze({
@@ -228,6 +229,7 @@ class Parser {
             ".type":   State.TYPE_NAME,
             ".table":  State.TABLE_NAME,
             ".elem":   State.ELEM_TABLE,
+            ".zero":   State.ZERO,
         };
         this.blocks = new Set(["block", "loop", "if"]);
         this.handlers = {
@@ -267,6 +269,7 @@ class Parser {
             [State.ELEM_TABLE]:   (token) => this.token_elem_table(token),
             [State.ELEM_ELEM]:    (token) => this.token_elem_elem(token),
             [State.ELEM_LABEL]:   (token) => this.token_elem_label(token),
+            [State.ZERO]:         (token) => this.token_zero(token),
         };
 
         this.results = [];
@@ -821,6 +824,26 @@ class Parser {
         return action;
     }
 
+	token_zero(token) {
+		if (token == LINE_END) {
+			console.error(
+				"ERROR: Unexpected newline in .zero, expected count")
+			this.state = State.TOP;
+			return;
+		}
+
+		const count = this.integer(token);
+		if (count == null) {
+			console.error(
+				`ERROR: Unexpected token ${token} in .zero, expected count`);
+			this.state = State.TOP;
+			return;
+		}
+
+		this.state = State.TOP;
+		return { type: Action.DATA, size: count, value: 0 }
+	}
+
     mem_action() {
         const action = {
             type: Action.MEM,