diff --git a/vendor/golang.org/x/text/unicode/rangetable/merge.go b/vendor/golang.org/x/text/unicode/rangetable/merge.go
new file mode 100644
index 0000000..ea2a080
--- /dev/null
+++ b/vendor/golang.org/x/text/unicode/rangetable/merge.go
@@ -0,0 +1,260 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package rangetable
+
+import (
+	"unicode"
+)
+
+// atEnd is used to mark a completed iteration.
+const atEnd = unicode.MaxRune + 1
+
+// Merge returns a new RangeTable that is the union of the given tables.
+// It can also be used to compact user-created RangeTables. The entries in
+// R16 and R32 for any given RangeTable should be sorted and non-overlapping.
+//
+// A lookup in the resulting table can be several times faster than using In
+// directly on the ranges. Merge is an expensive operation, however, and only
+// makes sense if one intends to use the result for more than a couple of
+// hundred lookups.
+func Merge(ranges ...*unicode.RangeTable) *unicode.RangeTable {
+	rt := &unicode.RangeTable{}
+	if len(ranges) == 0 {
+		return rt
+	}
+
+	iter := tablesIter(make([]tableIndex, len(ranges)))
+
+	for i, t := range ranges {
+		iter[i] = tableIndex{t, 0, atEnd}
+		if len(t.R16) > 0 {
+			iter[i].next = rune(t.R16[0].Lo)
+		}
+	}
+
+	if r0 := iter.next16(); r0.Stride != 0 {
+		for {
+			r1 := iter.next16()
+			if r1.Stride == 0 {
+				rt.R16 = append(rt.R16, r0)
+				break
+			}
+			stride := r1.Lo - r0.Hi
+			if (r1.Lo == r1.Hi || stride == r1.Stride) && (r0.Lo == r0.Hi || stride == r0.Stride) {
+				// Fully merge the next range into the previous one.
+				r0.Hi, r0.Stride = r1.Hi, stride
+				continue
+			} else if stride == r0.Stride {
+				// Move the first element of r1 to r0. This may eliminate an
+				// entry.
+				r0.Hi = r1.Lo
+				r0.Stride = stride
+				r1.Lo = r1.Lo + r1.Stride
+				if r1.Lo > r1.Hi {
+					continue
+				}
+			}
+			rt.R16 = append(rt.R16, r0)
+			r0 = r1
+		}
+	}
+
+	for i, t := range ranges {
+		iter[i] = tableIndex{t, 0, atEnd}
+		if len(t.R32) > 0 {
+			iter[i].next = rune(t.R32[0].Lo)
+		}
+	}
+
+	if r0 := iter.next32(); r0.Stride != 0 {
+		for {
+			r1 := iter.next32()
+			if r1.Stride == 0 {
+				rt.R32 = append(rt.R32, r0)
+				break
+			}
+			stride := r1.Lo - r0.Hi
+			if (r1.Lo == r1.Hi || stride == r1.Stride) && (r0.Lo == r0.Hi || stride == r0.Stride) {
+				// Fully merge the next range into the previous one.
+				r0.Hi, r0.Stride = r1.Hi, stride
+				continue
+			} else if stride == r0.Stride {
+				// Move the first element of r1 to r0. This may eliminate an
+				// entry.
+				r0.Hi = r1.Lo
+				r1.Lo = r1.Lo + r1.Stride
+				if r1.Lo > r1.Hi {
+					continue
+				}
+			}
+			rt.R32 = append(rt.R32, r0)
+			r0 = r1
+		}
+	}
+
+	for i := 0; i < len(rt.R16) && rt.R16[i].Hi <= unicode.MaxLatin1; i++ {
+		rt.LatinOffset = i + 1
+	}
+
+	return rt
+}
+
+type tableIndex struct {
+	t    *unicode.RangeTable
+	p    uint32
+	next rune
+}
+
+type tablesIter []tableIndex
+
+// sortIter does an insertion sort using the next field of tableIndex. Insertion
+// sort is a good sorting algorithm for this case.
+func sortIter(t []tableIndex) {
+	for i := range t {
+		for j := i; j > 0 && t[j-1].next > t[j].next; j-- {
+			t[j], t[j-1] = t[j-1], t[j]
+		}
+	}
+}
+
+// next16 finds the ranged to be added to the table. If ranges overlap between
+// multiple tables it clips the result to a non-overlapping range if the
+// elements are not fully subsumed. It returns a zero range if there are no more
+// ranges.
+func (ti tablesIter) next16() unicode.Range16 {
+	sortIter(ti)
+
+	t0 := ti[0]
+	if t0.next == atEnd {
+		return unicode.Range16{}
+	}
+	r0 := t0.t.R16[t0.p]
+	r0.Lo = uint16(t0.next)
+
+	// We restrict the Hi of the current range if it overlaps with another range.
+	for i := range ti {
+		tn := ti[i]
+		// Since our tableIndices are sorted by next, we can break if the there
+		// is no overlap. The first value of a next range can always be merged
+		// into the current one, so we can break in case of equality as well.
+		if rune(r0.Hi) <= tn.next {
+			break
+		}
+		rn := tn.t.R16[tn.p]
+		rn.Lo = uint16(tn.next)
+
+		// Limit r0.Hi based on next ranges in list, but allow it to overlap
+		// with ranges as long as it subsumes it.
+		m := (rn.Lo - r0.Lo) % r0.Stride
+		if m == 0 && (rn.Stride == r0.Stride || rn.Lo == rn.Hi) {
+			// Overlap, take the min of the two Hi values: for simplicity's sake
+			// we only process one range at a time.
+			if r0.Hi > rn.Hi {
+				r0.Hi = rn.Hi
+			}
+		} else {
+			// Not a compatible stride. Set to the last possible value before
+			// rn.Lo, but ensure there is at least one value.
+			if x := rn.Lo - m; r0.Lo <= x {
+				r0.Hi = x
+			}
+			break
+		}
+	}
+
+	// Update the next values for each table.
+	for i := range ti {
+		tn := &ti[i]
+		if rune(r0.Hi) < tn.next {
+			break
+		}
+		rn := tn.t.R16[tn.p]
+		stride := rune(rn.Stride)
+		tn.next += stride * (1 + ((rune(r0.Hi) - tn.next) / stride))
+		if rune(rn.Hi) < tn.next {
+			if tn.p++; int(tn.p) == len(tn.t.R16) {
+				tn.next = atEnd
+			} else {
+				tn.next = rune(tn.t.R16[tn.p].Lo)
+			}
+		}
+	}
+
+	if r0.Lo == r0.Hi {
+		r0.Stride = 1
+	}
+
+	return r0
+}
+
+// next32 finds the ranged to be added to the table. If ranges overlap between
+// multiple tables it clips the result to a non-overlapping range if the
+// elements are not fully subsumed. It returns a zero range if there are no more
+// ranges.
+func (ti tablesIter) next32() unicode.Range32 {
+	sortIter(ti)
+
+	t0 := ti[0]
+	if t0.next == atEnd {
+		return unicode.Range32{}
+	}
+	r0 := t0.t.R32[t0.p]
+	r0.Lo = uint32(t0.next)
+
+	// We restrict the Hi of the current range if it overlaps with another range.
+	for i := range ti {
+		tn := ti[i]
+		// Since our tableIndices are sorted by next, we can break if the there
+		// is no overlap. The first value of a next range can always be merged
+		// into the current one, so we can break in case of equality as well.
+		if rune(r0.Hi) <= tn.next {
+			break
+		}
+		rn := tn.t.R32[tn.p]
+		rn.Lo = uint32(tn.next)
+
+		// Limit r0.Hi based on next ranges in list, but allow it to overlap
+		// with ranges as long as it subsumes it.
+		m := (rn.Lo - r0.Lo) % r0.Stride
+		if m == 0 && (rn.Stride == r0.Stride || rn.Lo == rn.Hi) {
+			// Overlap, take the min of the two Hi values: for simplicity's sake
+			// we only process one range at a time.
+			if r0.Hi > rn.Hi {
+				r0.Hi = rn.Hi
+			}
+		} else {
+			// Not a compatible stride. Set to the last possible value before
+			// rn.Lo, but ensure there is at least one value.
+			if x := rn.Lo - m; r0.Lo <= x {
+				r0.Hi = x
+			}
+			break
+		}
+	}
+
+	// Update the next values for each table.
+	for i := range ti {
+		tn := &ti[i]
+		if rune(r0.Hi) < tn.next {
+			break
+		}
+		rn := tn.t.R32[tn.p]
+		stride := rune(rn.Stride)
+		tn.next += stride * (1 + ((rune(r0.Hi) - tn.next) / stride))
+		if rune(rn.Hi) < tn.next {
+			if tn.p++; int(tn.p) == len(tn.t.R32) {
+				tn.next = atEnd
+			} else {
+				tn.next = rune(tn.t.R32[tn.p].Lo)
+			}
+		}
+	}
+
+	if r0.Lo == r0.Hi {
+		r0.Stride = 1
+	}
+
+	return r0
+}