In presenter, handle the first line being soft-wrapped

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

spec/text-editor-presenter-spec.coffee

@@ -1522,6 +1522,15 @@ describe "TextEditorPresenter", ->
           expect(lineNumberStateForScreenRow(presenter, 7)).toBeDefined()
           expect(lineNumberStateForScreenRow(presenter, 8)).toBeUndefined()
 
+        it "correctly handles the first screen line being soft-wrapped", ->
+          editor.setSoftWrapped(true)
+          editor.setEditorWidthInChars(30)
+          presenter = new TextEditorPresenter(model: editor, height: 25, scrollTop: 50, lineHeight: 10, lineOverdrawMargin: 0)
+
+          expectValues lineNumberStateForScreenRow(presenter, 5), {screenRow: 5, bufferRow: 3, softWrapped: true}
+          expectValues lineNumberStateForScreenRow(presenter, 6), {screenRow: 6, bufferRow: 3, softWrapped: true}
+          expectValues lineNumberStateForScreenRow(presenter, 7), {screenRow: 7, bufferRow: 4, softWrapped: false}
+
         describe ".decorationClasses", ->
           it "adds decoration classes to the relevant line number state objects, both initially and when decorations change", ->
             marker1 = editor.markBufferRange([[4, 0], [6, 2]], invalidate: 'touch')

src/text-editor-presenter.coffee

@@ -237,22 +237,29 @@ class TextEditorPresenter
   updateLineNumbersState: ->
     startRow = @computeStartRow()
     endRow = @computeEndRow()
-    lastBufferRow = null
-    wrapCount = 0
     visibleLineNumberIds = {}
 
+    if startRow > 0
+      rowBeforeStartRow = startRow - 1
+      lastBufferRow = @model.bufferRowForScreenRow(rowBeforeStartRow)
+      wrapCount = rowBeforeStartRow - @model.screenRowForBufferRow(lastBufferRow)
+    else
+      lastBufferRow = null
+      wrapCount = 0
+
     for bufferRow, i in @model.bufferRowsForScreenRows(startRow, endRow - 1)
-      screenRow = startRow + i
-      top = screenRow * @lineHeight
       if bufferRow is lastBufferRow
         wrapCount++
-        softWrapped = true
         id = bufferRow + '-' + wrapCount
+        softWrapped = true
       else
-        wrapCount = 0
-        softWrapped = false
-        lastBufferRow = bufferRow
         id = bufferRow
+        wrapCount = 0
+        lastBufferRow = bufferRow
+        softWrapped = false
+
+      screenRow = startRow + i
+      top = screenRow * @lineHeight
       decorationClasses = @lineNumberDecorationClassesForRow(screenRow)
       foldable = @model.isFoldableAtScreenRow(screenRow)