No. To make Eyes of Ender which is necessary for activating the portal, you must craft them from Ender Pearls and Blaze Powder. You get Blaze Powder by crafting it with Blaze Rods, which you get from Blazes in the Nether. Unless you can spawn in Blazes in the Overworld using console commands, or hack in some items, or ask another player to give you some from their travels... no.

EDIT: See MatBat's answer, it's more accurate.

OLD ANSWER

You actually can.

Though it may be rare, Villager priest sell Eyes of Ender for a few emeralds. Therefore, if you have a lot of emeralds on hand, you can get to the End without entering the Nether.

One good thing to do to get these emeralds is to trade with Farmers for emeralds. They usually trade emeralds for common materials.

NEW ANSWER

As of this edit, you can no longer buy Eyes of Ender directly. Instead, you have to buy Ender Pearls, then craft the Eyes.

Yes you can, but...

Although this is horrificly rare. Each end portal fram block has a specific chance to be generated with an eye of ender already inplace. So in theory there is a chance to have a end portal that is completely kitted out with all blocks active. Since the amount of fortresses is limited there is a incredibly low chance for your world to have one of those.

In regards to the other answers: Sadly the cleric villagers only sell Ender pearly and not eye of ender, therefore you will still need blaze powder, which as far as I was able to find, cannot be found in loot chests of any kind nor through any amount of crafting except from blaze rods, which themself can only be obtained from blazes in the nether.

So in practical sense there is no way to pass on the nether if you want to reach end game :)