Fix various print inefficiencies/bugs

packages/babel-generator/src/generators/statements.js

@@ -107,7 +107,12 @@ function buildLabelStatement(prefix, key = "label") {
 
     let label = node[key];
     if (label) {
-      this.push(" ");
+      if (!(this.format.minified && (t.isUnaryExpression(label, { prefix: true }) ||
+                                     t.isUpdateExpression(label, { prefix: true })))) {
+        this.push(" ");
+
+      }
+
       let terminatorState = this.startTerminatorless();
       this.print(label, node);
       this.endTerminatorless(terminatorState);
@@ -153,7 +158,8 @@ export function CatchClause(node: Object) {
   this.keyword("catch");
   this.push("(");
   this.print(node.param, node);
-  this.push(") ");
+  this.push(")");
+  this.space();
   this.print(node.body, node);
 }
 

packages/babel-generator/src/node/parentheses.js

@@ -123,6 +123,22 @@ export function SequenceExpression(node: Object, parent: Object): boolean {
     return false;
   }
 
+  if (t.isSwitchStatement(parent) && parent.discriminant === node) {
+    return false;
+  }
+
+  if (t.isWhileStatement(parent) && parent.test === node) {
+    return false;
+  }
+
+  if (t.isIfStatement(parent) && parent.test === node) {
+    return false;
+  }
+
+  if (t.isForInStatement(parent) && parent.right === node) {
+    return false;
+  }
+
   // Otherwise err on the side of overparenthesization, adding
   // explicit exceptions above if this proves overzealous.
   return true;

packages/babel-generator/test/fixtures/minified/labeled-statement/actual.js

@@ -0,0 +1,7 @@
+function x() {
+  return -1;
+  return --i;
+  return !2;
+}
+
+throw -1;

packages/babel-generator/test/fixtures/minified/labeled-statement/expected.js

@@ -0,0 +1 @@
+function x(){return-1;return--i;return!2}throw-1;

packages/babel-generator/test/fixtures/parentheses/sequence-expressions/actual.js

@@ -0,0 +1,13 @@
+function foo() {
+  return a, b;
+}
+
+if (a, b, c) d();
+
+throw a, b, c;
+
+switch (a, b, c) {}
+
+for (a in b, c);
+
+while (a, b, c);

packages/babel-generator/test/fixtures/parentheses/sequence-expressions/expected.js

@@ -0,0 +1,13 @@
+function foo() {
+  return a, b;
+}
+
+if (a, b, c) d();
+
+throw a, b, c;
+
+switch (a, b, c) {}
+
+for (a in b, c);
+
+while (a, b, c);